U.S. patent application number 15/005567 was filed with the patent office on 2016-05-19 for use of peracetic acid/hydrogen peroxide and peroxide-reducing agents for treatment of drilling fluids, frac fluids, flowback water and disposal water.
The applicant listed for this patent is Ecolab USA Inc.. Invention is credited to Renato De Paula, Brandon Herdt, Victor Keasler, Junzhong Li, David D. McSherry, Robert J. Ryther, Richard Staub.
Application Number | 20160137535 15/005567 |
Document ID | / |
Family ID | 49235305 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160137535 |
Kind Code |
A1 |
Keasler; Victor ; et
al. |
May 19, 2016 |
USE OF PERACETIC ACID/HYDROGEN PEROXIDE AND PEROXIDE-REDUCING
AGENTS FOR TREATMENT OF DRILLING FLUIDS, FRAC FLUIDS, FLOWBACK
WATER AND DISPOSAL WATER
Abstract
Methods for the use of peracid compositions having decreased
hydrogen peroxide concentration and a UV-blocking agent for various
water treatments, including oil- and gas-field operations, and/or
other aseptic treatments are disclosed. In numerous aspects,
peracetic acid is the preferred peracid and is treated with a
peroxide-reducing agent to substantially reduce the hydrogen
peroxide content. Methods for using the treated peracid
compositions for treatment of drilling fluids, frac fluids, flow
back waters and disposal waters are also disclosed for improving
water condition, reducing oxidizing damage associated with hydrogen
peroxide and/or reducing bacteria infestation
Inventors: |
Keasler; Victor; (Sugarland,
TX) ; De Paula; Renato; (Houston, TX) ; Li;
Junzhong; (Eagan, MN) ; McSherry; David D.;
(St. Paul, MN) ; Herdt; Brandon; (Hastings,
MN) ; Staub; Richard; (Lakeville, MN) ;
Ryther; Robert J.; (St. Paul, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ecolab USA Inc. |
St. Paul |
MN |
US |
|
|
Family ID: |
49235305 |
Appl. No.: |
15/005567 |
Filed: |
January 25, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13798307 |
Mar 13, 2013 |
9242879 |
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15005567 |
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61617814 |
Mar 30, 2012 |
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13798307 |
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Current U.S.
Class: |
166/305.1 ;
210/757 |
Current CPC
Class: |
C02F 1/722 20130101;
E21B 43/00 20130101; C09K 2208/32 20130101; A01N 25/32 20130101;
C02F 2303/18 20130101; C09K 8/605 20130101; C02F 2305/02 20130101;
C02F 1/50 20130101; A01N 25/22 20130101; A01N 37/16 20130101; A01N
37/16 20130101; C02F 1/70 20130101; A01N 59/00 20130101; C02F
2103/08 20130101; C02F 2103/10 20130101; Y02W 10/37 20150501; C09K
8/66 20130101; C02F 2303/04 20130101; C02F 3/342 20130101; C02F
2303/08 20130101; C02F 1/76 20130101; C09K 2208/28 20130101; C02F
2103/365 20130101; C02F 2303/20 20130101; E21B 21/068 20130101 |
International
Class: |
C02F 1/70 20060101
C02F001/70; C02F 1/72 20060101 C02F001/72; E21B 21/06 20060101
E21B021/06; C02F 3/34 20060101 C02F003/34; E21B 43/00 20060101
E21B043/00; C02F 1/50 20060101 C02F001/50; C02F 1/76 20060101
C02F001/76 |
Claims
1. A method of treating waters comprising: treating a percarboxylic
acid composition with a peroxide-reducing enzyme to generate an
antimicrobial composition; providing the antimicrobial composition
to a water source in need of treatment to form a treated water
source, wherein the antimicrobial composition and/or the treated
water source further comprises a UV-blocking agent, and wherein the
treated water source comprises (i) from up to about 1000 ppm
catalase enzyme, (ii) from about 0 wt-% to about 1 wt-% hydrogen
peroxide; (iii) from about 0.0001 wt-% to about 10.0 wt-% of a
C.sub.1-C.sub.22 carboxylic acid; and (iv) from about 0.0001 wt-%
to about 10.0 wt-% of a C.sub.1-C.sub.22 percarboxylic acid,
wherein the hydrogen peroxide to peracid ratio is from about 0:100
to about 1:10 by wt; and directing the treated water source into a
subterranean environment or disposing of the treated water source
having a minimized environmental impact.
2. The method of claim 1, wherein the UV-blocking agent is a
natural or synthetic dye, and wherein water source in need of
treatment is selected from the group consisting of fresh water,
pond water, sea water, produced water and combinations thereof.
3. The method of claim 2, wherein the UV-blocking agent is a
cationic dye, and wherein the water source is at least 1 wt-%
produced water and wherein antimicrobial efficacy of the
antimicrobial composition on the treated water source is superior
to antimicrobial effects of a water source that does not contain
produced water.
4. The method of claim 1, wherein the treating of the percarboxylic
acid composition with the peroxide-reducing agent to generate the
antimicrobial composition is not a pretreatment step and occurs
within the water source in need of treatment.
5. The method of claim 1, wherein the treated water reduces
corrosion caused by hydrogen peroxide and reduces microbial-induced
corrosion, and wherein the antimicrobial composition does not
interfere with friction reducers, viscosity enhancers, other
functional ingredients found in the water source, or combinations
thereof.
6. The method of claim 1, wherein the percarboxylic acid stability
is improved through the pretreatment step to minimize hydrogen
peroxide concentration within the percarboxylic acid composition
from about 0 wt-% to about 0.5 wt-% hydrogen peroxide, and wherein
the concentration of the C.sub.1-C.sub.22 carboxylic acid is from
about 0.0001 wt-% to about 5.0 wt-%, and wherein the concentration
of the C.sub.1-C.sub.22 percarboxylic acid is from about 0.0001
wt-% to about 5.0 wt-%.
7. The method of claim 1, wherein the percarboxylic acid is
peracetic acid, wherein the carboxylic acid is acetic acid, and
wherein the UV-blocking agent is methylene blue.
8. The method of claim 1, wherein an acidulant is added to the
water source in need of treatment before the addition of the
antimicrobial composition to a water source.
9. A method of treating a water source comprising: adding a
percarboxylic acid composition, a peroxide-reducing agent and a
UV-blocking agent to a water source to form a treated water source
having a hydrogen peroxide to peracid ratio from about 0:100 to
about 1:10 by weight, wherein said antimicrobial composition in a
use solution with said treated water source comprises (i) less than
about 1000 ppm of a catalase enzyme, (ii) from about 0 wt-% to
about 1 wt-% hydrogen peroxide; (iii) from about 0.0001 wt-% to
about 10.0 wt-% of a C.sub.1-C.sub.22 carboxylic acid; (iv) from
about 0.0001 wt-% to about 10.0 wt-% of a C.sub.1-C.sub.22
percarboxylic acid; and (v) from about 0.00001 wt-% to about 5 wt-%
of said UV-blocking agent; and wherein the treated water source
reduces corrosion caused by hydrogen peroxide and reduces
microbial-induced corrosion, and wherein the antimicrobial
composition does not interfere with friction reducers, viscosity
enhancers, other functional ingredients found in the water source
or combinations thereof.
10. The method of claim 9, wherein the UV-blocking agent is a
natural or synthetic dye, and wherein the water source is fresh
water, pond water, sea water, produced water or combinations
thereof.
11. The method of claim 10, wherein use of said produced water in
the water source further includes a first pretreatment of a
percarboxylic acid antimicrobial composition with the
peroxide-reducing agent, wherein the peroxide-reducing agent is a
metal to provide the antimicrobial composition, wherein said
composition provides superior antimicrobial efficacy in comparison
to a water source that does not contain produced water.
12. The method of claim 9, further comprising a first pretreatment
step wherein a percarboxylic acid composition is contacted by the
peroxide-reducing agent to generate a pretreated antimicrobial
composition.
13. The method of claim 9, further comprising the step of directing
the treated water source into a subterranean environment or
disposing of the treated water source having a minimized
environmental impact.
14. The method of claim 9, wherein the percarboxylic acid stability
is improved through the reduction of hydrogen peroxide
concentration as a result of the addition of the peroxide-reducing
agent.
15. The method of claim 9, wherein the percarboxylic acid is
peracetic acid, wherein the carboxylic acid is acetic acid, and
wherein the UV-blocking agent is methylene blue.
16. The method of claim 9, wherein the adding of the percarboxylic
acid composition and the peroxide-reducing agent to the water
source occurs on an at least every 5 day dosing cycle.
17. The method of claim 9, wherein an acidulant is added to the
water source in need of treatment before the addition of the
percarboxylic acid and peroxide-reducing agent to the water
source.
18. A method of treating a water source comprising: a first step of
either treating a percarboxylic acid composition with a
peroxide-reducing agent to generate an antimicrobial composition or
adding a percarboxylic acid and peroxide-reducing agent to a water
source, wherein said peroxide-reducing agent is an enzyme;
obtaining a water source in need of treatment; forming a treated
water source, wherein the treated water source comprises (i) from
up to about 1000 ppm peroxide-reducing agent, (ii) from about 0
wt-% to about 1 wt-% hydrogen peroxide; (iii) from about 0.0001
wt-% to about 10.0 wt-% of a C.sub.1-C.sub.22 carboxylic acid; (iv)
from about 0.0001 wt-% to about 10.0 wt-% of a C.sub.1-C.sub.22
percarboxylic acid; and (v) from about 0.00001 wt-% to about 5 wt-%
of a UV-blocking agent, wherein the hydrogen peroxide to peracid
ratio is from about 0:100 to about 1:10 by wt; and directing the
treated water source into a subterranean environment or disposing
of the treated water source having a minimized environmental
impact, wherein the treated water source reduces corrosion caused
by hydrogen peroxide, reduces microbial-induced corrosion, and does
not interfere with friction reducers, viscosity enhancers, or other
functional ingredients found in the water source.
19. The method of claim 18, wherein the UV-blocking agent is a
cationic dye and wherein the inorganic peroxide-reducing agent is a
metal selected from the group consisting of iron, copper and
manganese.
20. The method of claim 18, wherein the UV-blocking agent is
methylene blue and wherein the inorganic peroxide-reducing agent is
a halide.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation application of U.S. Ser.
No. 13/798,307 filed Mar. 13, 2013, which is a continuation-in-part
application of U.S. Provisional Application No. 61/617,814, filed
Mar. 30, 2012, titled "Use of Peracetic Acid/Hydrogen Peroxide and
Catalase for Treatment of Drilling Fluids, Frac Fluids, Flowback
Water and Disposal Water," which is herein incorporated by
reference in its entirety.
[0002] This application is also related to U.S. patent application
Ser. No. 13/798,281, entitled "Use of Peracetic Acid/Hydrogen
Peroxide and Peroxide-Reducing Enzymes for Treatment of Drilling
Fluids, Frac Fluids, Flow Back Water and Disposal Water," U.S.
patent application Ser. No. 13/798,311, entitled "Use of Peracetic
Acid/Hydrogen Peroxide and Peroxide-Reducing Agents for Treatment
Of Drilling Fluids, Frac Fluids, Flow Back Water and Disposal
Water," and U.S. Patent Application Ser. No. 61/710,631, filed Oct.
5, 2012, and titled "Stable Peroxycarboxylic Acid Compositions and
Uses Thereof," each of which are filed concurrently herewith. The
entire contents of these patent applications are hereby expressly
incorporated herein by reference including, without limitation, the
specification, claims, and abstract, as well as any figures,
tables, or drawings thereof.
FIELD OF THE INVENTION
[0003] The present disclosure relates to percarboxylic acid
compositions and methods for the use of peracid compositions with
decreased hydrogen peroxide concentrations for various water
treatments and UV-blocking agents, including oil- and gas-field
operations, and/or other aseptic treatments. The present invention
also relates to slick water compositions and gel based compositions
that comprise stable percarboxylic acid compositions and the use
thereof in oil- and gas-field operations. In numerous aspects,
peracetic acid is the preferred peracid and is treated with a
peroxide-reducing agent, such as a metal or strong oxidizer, to
substantially reduce the hydrogen peroxide content. The methods of
treatment are particularly suitable for treatment of drilling
fluids, frac fluids, flow back waters and/or disposal waters for
improving water condition, reducing oxidizing damage associated
with hydrogen peroxide and/or reducing bacteria infestation.
BACKGROUND OF THE INVENTION
[0004] Peroxycarboxylic acids (also referred to as peracids), as
well as mixed peroxycarboxylic acid systems, are known for use as
antimicrobials and bleaching agents in a variety of industries.
Peracetic acid or peroxyacetic acid (PAA or POAA) (dynamic
equilibrium mixture of POAA/PAA, H.sub.2O.sub.2, H.sub.2O and AA)
have been used in the food and beverage industries as a fast
acting, "green" antimicrobial. Such products demonstrate beneficial
properties towards oxidizing solids and improving water quality. In
addition, compared to other commercially available biocides, the
use of peracetic acid results in a low environmental footprint due
in part to its decomposition into innocuous components (e.g. acetic
acid (AA), oxygen, CO.sub.2 and H.sub.2O). See for example, U.S.
Pat. No. 8,226,939, entitled "Antimicrobial Peracid Compositions
with Selected Catalase Enzymes and Methods of Use in Aseptic
Packaging," which is incorporated by reference in its entirety.
[0005] Peracids have also been used for certain water treatment
applications. However, these have been very limited in the area of
commercial well drilling operations. See for example U.S. Patent
Publication No. 2010/0160449, entitled "Peracetic Acid Oil-Field
Biocide and Method," and U.S. Pat. No. 7,156,178 which are
incorporated by reference in their entirety. However, particular
water treatment applications present difficulties for the use of
peracids during several steps of the oil and gas production
methods, including for example microbial efficacy and compatibility
concerns. For example, despite its fast action and eco-friendly
properties, the use of peracids, including peracetic acid, has a
number of limitations for use in water treatment methods. High
dosages of the peracid can increase the corrosion rates in
pipelines and equipment due in part to the presence of hydrogen
peroxide (H.sub.2O.sub.2). Moreover, the peracids/H.sub.2O.sub.2
can interfere with the activity of functional agents necessary for
the methods of water treatment in oil and gas recovery, including
friction reducers and thickeners which are often critical for the
fracking process. In addition, peracids and hydrogen peroxide are
prone to quenching from common, naturally occurring chemicals which
can severely limit their utility.
[0006] There remains a need for enhanced water treatment methods.
For example, from a microbiology perspective, mitigation of
microorganisms is essential to minimize environmental concerns for
waste products and to avoid contamination of systems, such as well
or reservoir souring and/or microbiologically-influenced corrosion
(MIC). As a result, prior to the drilling and fracking steps, water
is treated to restrict the introduction of microbes into the well
or reservoir. This also acts to prevent microbes from having a
negative effect on the integrity of the fluids. In addition, before
disposal, flow-back water is treated to abide environmental
restrictions stipulated by regulatory agencies.
[0007] Accordingly, it is an objective of the invention to replace
conventional oxidizing biocides for water treatments, such as
typical equilibrium peracetic acid, hypochlorite or hypochlorous
acid, and/or chlorine dioxide compositions.
[0008] It is a further objective of the invention to develop
methods for water treatment in oil and gas recovery that provide
effective antimicrobial efficacy without any deleterious
interaction with functional agents, including for example friction
reducers and viscosity enhancers.
[0009] A further objective of the invention is to develop
compositions and methods for use of atypical peracids via
distillation, perhydrolysis of acetyl donors, and preferably use of
peroxide-reducing agents, such as a metal or strong oxidizer, to
improve the stability of peracids and peracid compositions and in
most cases the antimicrobial efficacy of the peracid compared to
the use of conventional equilibrium peracids alone.
[0010] A further objective of the invention is to develop methods
using peracids for the treatment of water used in drilling and/or
fracking, as well as treatment of water that is planned for
disposal to result in cleaner water with low numbers of
microorganisms.
[0011] A still further objective of the invention are compositions
and methods for using peracids, namely peracetic acid, with a
peroxide-reducing agent, such as a metal or strong oxidizer, to
reduce H.sub.2O.sub.2 in order to minimize the negative effects of
H.sub.2O.sub.2.
[0012] In yet a still further aspect, the compositions and methods
of the invention are used for minimizing and/or eliminating the
negative effects of UV (e.g. sunlight) in the treatment of water
used in drilling and/or fracking that employ peroxide-reducing
enzymes.
[0013] Other objects, advantages and features of the present
invention will become apparent from the following specification
taken in conjunction with the accompanying drawings.
BRIEF SUMMARY OF THE INVENTION
[0014] In an aspect, the present invention provides a method of
treating waters comprising: (a) treating a percarboxylic acid
composition with a peroxide-reducing agent to generate an
antimicrobial composition; (b) providing the antimicrobial
composition to a water source in need of treatment to form a
treated water source, wherein the antimicrobial composition and/or
the treated water source further comprises a UV-blocking agent, and
wherein the treated water source comprises (i) from up to about
1000 ppm peroxide-reducing enzyme, (ii) from about 0 wt-% to about
1 wt-% hydrogen peroxide; (iii) from about 0.0001 wt-% to about
10.0 wt-% of a C1-C22 carboxylic acid; and (iv) from about 0.0001
wt-% to about 10.0 wt-% of a C1-C22 percarboxylic acid, wherein the
hydrogen peroxide to peracid ratio is from about 0:100 to about
1:10 by wt; and (c) directing the treated water source into a
subterranean environment or disposing of the treated water source
having a minimized environmental impact.
[0015] In a further aspect, the present invention provides a method
of treating a water source comprising: adding a percarboxylic acid
and peroxide-reducing enzyme to the water source to form a treated
water source having a hydrogen peroxide to peracid ratio from about
0:100 to about 1:10 by weight, wherein said antimicrobial
composition in a use solution with said treated water source
comprises (i) less than about 1000 ppm of a catalase enzyme, (ii)
from about 0 wt-% to about 1 wt-% hydrogen peroxide; (iii) from
about 0.0001 wt-% to about 10.0 wt-% of a C.sub.1-C.sub.22
carboxylic acid; (iv) from about 0.0001 wt-% to about 10.0 wt-% of
a C.sub.1-C.sub.22 percarboxylic acid; and (v) from about 0.00001
wt-% to about 5 wt-% of said UV-blocking agent. In a further
aspect, the treated water source reduces corrosion caused by
hydrogen peroxide and reduces microbial-induced corrosion, and
wherein the antimicrobial composition does not interfere with
friction reducers, viscosity enhancers, other functional
ingredients found in the water source or combinations thereof.
[0016] Surprisingly, it has been found that the inclusion of a
UV-blocking agent further enhances the efficacy of the
peroxide-reducing enzymes, such as catalase enzymes, are
particularly effective at decomposing hydrogen peroxide in peracid
compositions and in particular in peracid compositions that are
used in water treatments for oil and gas recovery in the presence
of the UV-blocking agent.
[0017] Methods and compositions for using decreased amounts/ratio
of hydrogen peroxide (to peracid) provide unexpected benefits in
the stability (and as an apparent result, further unexpected
benefits in the efficacy) of the oxidizing biocides. In turn the
reduced available oxygen within the peracid composition does not
negatively interact with functional agents, including for example
friction reducers, and provides a number of additional benefits for
use in industrial applications and/or various aseptic treatment
applications.
[0018] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention.
Accordingly, the drawings and detailed description are to be
regarded as illustrative in nature and not restrictive.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIGS. 1-2 show an embodiment of the invention where use of
peracid with catalase decreases the corrosion rates of carbon
steel.
[0020] FIG. 3 shows the average log reduction generated after a 2.5
minute and 5 minute exposure time to varying concentrations of POAA
required to achieve 20 ppm residual POAA within various fracking
water mixtures.
[0021] FIG. 4 shows the biocide efficiency of PAA/H.sub.2O.sub.2
and PAA/H.sub.2O.sub.2/Catalase compositions after a 10 minute
contact period according to an embodiment of the invention.
[0022] FIG. 5 shows the biocide efficiency of PAA/H.sub.2O.sub.2
and PAA/H.sub.2O.sub.2/Catalase compositions after a 60 minute
contact period according to an embodiment of the invention.
[0023] FIG. 6 shows the average log reduction generated after a 2.5
minute exposure time to varying concentrations of POAA to achieve
20 ppm residual POAA within fracking water mixtures.
[0024] FIG. 7 shows the average log reduction generated after a 2.5
minute exposure time to 30 ppm or 40 ppm POAA EnviroSan with or
without catalase in different fracking water mixtures according to
embodiments of the invention.
[0025] FIG. 8 shows titration data of POAA in catalase treated (and
untreated) solutions of the EnviroSan test substance according to
embodiments of the invention.
[0026] FIG. 9 shows the average log reduction generated after a 2.5
minute exposure time to 30 ppm POAA EnviroSan with or without
catalase pretreatment in different fracking water mixtures
according to the invention.
[0027] FIG. 10 shows the average log reduction generated after a 5
minute exposure time to 30 ppm POAA EnviroSan with or without
catalase pretreatment in different fracking water mixtures
according to the invention.
[0028] FIG. 11 shows the average log reduction generated after a 5
minute exposure time to 30 ppm POAA EnviroSan with or without
catalase in different fracking water mixtures that were pretreated
with 500 ppm EnviroSan product more than 1 hour before micro
testing.
[0029] FIG. 12 shows the log survivors present 2.5, 5 and 60
minutes after the addition of a P. aeruginosa culture into
different mixtures of fracking water according to embodiments of
the invention.
[0030] FIG. 13 shows the average log reduction generated after a
2.5 and 5 minute exposure times to 30 ppm PAA with catalase against
increasing levels of PAA alone in various fracking water
mixtures.
[0031] FIG. 14 shows the impact of POAA to H.sub.2O.sub.2 ratio on
the stability of POAA according to embodiments of the
invention.
[0032] FIGS. 15-16 show the impact of catalase addition on the
peracid stability within treatment waters according to the
invention.
[0033] FIG. 17 shows the synergy of mixed peracid antimicrobial
efficacy with blends of water sources according to embodiments of
the invention.
[0034] FIG. 18 shows the compatibility of peracid and catalase
compositions for use in gel formation for gel frac fluids according
to embodiments of the invention.
[0035] FIG. 19 shows the compatibility of peracid and catalase
compositions as a result of processes of combining the same to
produce reduced peroxide peracid compositions according to
embodiments of the invention.
[0036] FIG. 20 shows the impact on peracid composition stability in
various pretreated contaminated water sources according to
embodiments of the invention.
[0037] FIG. 21 shows differences in POAA composition stability
according to embodiments of the invention.
[0038] FIG. 22 shows the difference in POAA decomposition within a
peracid composition treated with an inorganic metal
peroxide-reducing agent, wherein the peracid compositions have
varying concentrations of hydrogen peroxide.
[0039] FIG. 23 shows the loss rate of POAA concentration in the
presence of a platinum peroxide-reducing agent.
[0040] FIG. 24 shows the decomposition of POAA compositions treated
with a platinum peroxide-reducing agent (with/without a catalase
peroxide-reducing enzyme agent) according to embodiments of the
invention.
[0041] FIG. 25 shows the decomposition of POAA and hydrogen
peroxide in peracid compositions treated with various metallic
catalysts (e.g. peroxide-reducing agents) according to embodiments
of the invention.
[0042] FIGS. 26-27 show POAA loss (FIG. 26) and hydrogen peroxide
loss (FIG. 27) as a function of time in the presence of a CoMo
peroxide-reducing agent according to embodiments of the
invention.
[0043] FIGS. 28-29 show POAA loss (FIG. 28) and hydrogen peroxide
loss (FIG. 29) as a function of time in the presence of a NiW
peroxide-reducing agent according to embodiments of the
invention.
[0044] FIGS. 30-33 show POAA loss (FIGS. 30, 32, 33) and hydrogen
peroxide loss (FIGS. 31-33) as a function of time in the presence
of a NiMo peroxide-reducing agent according to embodiments of the
invention.
[0045] FIGS. 34-37 show POAA loss (FIGS. 34, 36, 37) and hydrogen
peroxide loss (FIGS. 35-37) as a function of time in the presence
of a Mo peroxide-reducing agent according to embodiments of the
invention.
[0046] Various embodiments of the present invention will be
described in detail with reference to the drawings, wherein like
reference numerals represent like parts throughout the several
views. Reference to various embodiments does not limit the scope of
the invention. Figures represented herein are not limitations to
the various embodiments according to the invention and are
presented for exemplary illustration of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] The present disclosure relates to peracid compositions with
low to substantially no hydrogen peroxide for use in water
treatments. In particular, peroxycarboxylic acids treated with a
peroxide-reducing agent, such as a catalase enzyme, to reduce
and/or eliminate hydrogen peroxide from the peroxycarboxylic acid
are provided, as well as methods for treating various water sources
with the same for the use in oil and gas recovery.
[0048] The methods and compositions disclosed herein have many
advantages over conventional, peracid compositions used for water
treatment and/or other antimicrobial treatments. For example, the
peracid compositions treated with a peroxide-reducing agent such as
a peroxide-reducing enzyme (or other means to substantially reduce
hydrogen peroxide content) according to methods disclosed herein,
have significantly lower levels of the oxidant hydrogen peroxide.
Beneficially, the reduction and/or elimination of hydrogen peroxide
compared to un-treated peracid compositions provides improved
antimicrobial efficacy, eliminates deleterious interaction with
friction reducers and other functional ingredients used in water
treatments, and/or reduces the environmental impact of treated
waters when eliminated. In addition, the treated peracid
compositions have greatly reduced off gassing potential and
continue to prevent well and reservoir souring as well as prevent
microbiologically-influenced corrosion. These and other benefits of
the present invention are disclosed herein.
[0049] The embodiments of this invention are not limited to
particular peroxycarboxylic acid compositions (preferably treated
with a peroxide-reducing agent, such as a catalase to reduce
hydrogen peroxide) and methods for using the same, which can vary
and are understood by skilled artisans. It is further to be
understood that all terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting in any manner or scope. For example, all units, prefixes,
and symbols may be denoted in its SI accepted form. Numeric ranges
recited within the specification are inclusive of the numbers
defining the range and include each integer within the defined
range.
[0050] It should be noted that, as used in this specification and
the appended claims, the singular forms "a," "an," and "the"
include plural referents unless the content clearly dictates
otherwise. Thus, for example, reference to a composition containing
"a compound" includes a composition having two or more compounds.
It should also be noted that the term "or" is generally employed in
its sense including "and/or" unless the content clearly dictates
otherwise.
[0051] So that the present invention may be more readily
understood, certain terms are first defined. Unless defined
otherwise, all technical and scientific terms used herein have the
same meaning as commonly understood by one of ordinary skill in the
art to which embodiments of the invention pertain. Many methods and
materials similar, modified, or equivalent to those described
herein can be used in the practice of the embodiments of the
present invention without undue experimentation, the preferred
materials and methods are described herein. In describing and
claiming the embodiments of the present invention, the following
terminology will be used in accordance with the definitions set out
below.
[0052] Throughout this disclosure, various aspects of this
invention are presented in a range format. It should be understood
that the description in range format is merely for convenience and
brevity and should not be construed as an inflexible limitation on
the scope of the invention. Accordingly, the description of a range
should be considered to have specifically disclosed all the
possible sub-ranges as well as individual numerical values within
that range. For example, description of a range such as from 1 to 6
should be considered to have specifically disclosed sub-ranges such
as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6,
from 3 to 6 etc., as well as individual numbers within that range,
for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the
breadth of the range.
[0053] As used herein, the term "about" refers to variation in the
numerical quantity that can occur, for example, through typical
measuring and liquid handling procedures used for making
concentrates or use solutions in the real world; through
inadvertent error in these procedures; through differences in the
manufacture, source, or purity of the ingredients used to make the
compositions or carry out the methods; and the like. The term
"about" also encompasses amounts that differ due to different
equilibrium conditions for a composition resulting from a
particular initial mixture. Whether or not modified by the term
"about", the claims include equivalents to the quantities.
[0054] The term "cleaning," as used herein, means to perform or aid
in soil removal, bleaching, microbial population reduction, or
combination thereof. For the purpose of this patent application,
successful microbial reduction is achieved when the microbial
populations are reduced by at least about 50%, or by significantly
more than is achieved by a wash with water. Larger reductions in
microbial population provide greater levels of protection.
[0055] As used herein, "consisting essentially of" means that the
methods and compositions may include additional steps, components,
ingredients or the like, but only if the additional steps,
components and/or ingredients do not materially alter the basic and
novel characteristics of the claimed methods and compositions. It
is understood that aspects and embodiments of the invention
described herein include "consisting" and/or "consisting
essentially of" aspects and embodiments.
[0056] As used herein, the term "disinfectant" refers to an agent
that kills all vegetative cells including most recognized
pathogenic microorganisms, using the procedure described in
A.O.A.C. Use Dilution Methods, Official Methods of Analysis of the
Association of Official Analytical Chemists, paragraph 955.14 and
applicable sections, 15th Edition, 1990 (EPA Guideline 91-2). As
used herein, the term "high level disinfection" or "high level
disinfectant" refers to a compound or composition that kills
substantially all organisms, except high levels of bacterial
spores, and is effected with a chemical germicide cleared for
marketing as a sterilant by the Food and Drug Administration. As
used herein, the term "intermediate-level disinfection" or
"intermediate level disinfectant" refers to a compound or
composition that kills mycobacteria, most viruses, and bacteria
with a chemical germicide registered as a tuberculocide by the
Environmental Protection Agency (EPA). As used herein, the term
"low-level disinfection" or "low level disinfectant" refers to a
compound or composition that kills some viruses and bacteria with a
chemical germicide registered as a hospital disinfectant by the
EPA.
[0057] As used herein, the term "free," "no," "substantially no" or
"substantially free" refers to a composition, mixture, or
ingredient that does not contain a particular compound or to which
a particular compound or a particular compound-containing compound
has not been added. According to the invention, the reduction
and/or elimination of hydrogen peroxide according to embodiments
provide hydrogen peroxide-free or substantially-free compositions.
Should the particular compound be present through contamination
and/or use in a minimal amount of a composition, mixture, or
ingredients, the amount of the compound shall be less than about 3
wt-%. More preferably, the amount of the compound is less than 2
wt-%, less than 1 wt-%, and most preferably the amount of the
compound is less than 0.5 wt-%.
[0058] As used herein, the term "microorganism" refers to any
noncellular or unicellular (including colonial) organism.
Microorganisms include all prokaryotes. Microorganisms include
bacteria (including cyanobacteria), spores, lichens, fungi,
protozoa, virinos, viroids, viruses, phages, and some algae. As
used herein, the term "microbe" is synonymous with
microorganism.
[0059] As used herein, the terms "mixed" or "mixture" when used
relating to "percarboxylic acid composition," "percarboxylic
acids," "peroxycarboxylic acid composition" or "peroxycarboxylic
acids" refer to a composition or mixture including more than one
percarboxylic acid or peroxycarboxylic acid.
[0060] As used herein, the term "sanitizer" refers to an agent that
reduces the number of bacterial contaminants to safe levels as
judged by public health requirements. In an embodiment, sanitizers
for use in this invention will provide at least a 99.999% reduction
(5-log order reduction). These reductions can be evaluated using a
procedure set out in Germicidal and Detergent Sanitizing Action of
Disinfectants, Official Methods of Analysis of the Association of
Official Analytical Chemists, paragraph 960.09 and applicable
sections, 15th Edition, 1990 (EPA Guideline 91-2). According to
this reference a sanitizer should provide a 99.999% reduction
(5-log order reduction) within 30 seconds at room temperature,
25.+-.2.degree. C., against several test organisms.
[0061] Differentiation of antimicrobial "-cidal" or "-static"
activity, the definitions which describe the degree of efficacy,
and the official laboratory protocols for measuring this efficacy
are considerations for understanding the relevance of antimicrobial
agents and compositions. Antimicrobial compositions can affect two
kinds of microbial cell damage. The first is a lethal, irreversible
action resulting in complete microbial cell destruction or
incapacitation. The second type of cell damage is reversible, such
that if the organism is rendered free of the agent, it can again
multiply. The former is termed microbiocidal and the later,
microbistatic. A sanitizer and a disinfectant are, by definition,
agents which provide antimicrobial or microbiocidal activity. In
contrast, a preservative is generally described as an inhibitor or
microbistatic composition
[0062] As used herein, the term "water" for treatment according to
the invention includes a variety of sources, such as freshwater,
pond water, sea waters, salt water or brine source, brackish water,
recycled water, or the like. Waters are also understood to
optionally include both fresh and recycled water sources (e.g.
"produced waters"), as well as any combination of waters for
treatment according to the invention.
[0063] As used herein, "weight percent," "wt-%," "percent by
weight," "% by weight," and variations thereof refer to the
concentration of a substance as the weight of that substance
divided by the total weight of the composition and multiplied by
100. It is understood that, as used here, "percent," "%," and the
like are intended to be synonymous with "weight percent," "wt-%,"
etc.
Embodiments of the Invention
[0064] The invention generally relates to the use of
peroxide-reducing agents enzymes, such as catalase or peroxidase
enzymes, for use with peracid compositions, and in particular
catalase enzymes in peracid compositions. The invention uses the
peroxide-reducing enzymes with peracid compositions for use in
water treatments in the field of oil and gas recovery. The
invention further relates to the use of additional methods to
reduce and/or eliminate hydrogen peroxide from peracids to provide
similar benefits to a peracid composition. Additional methods which
produce a very low hydrogen peroxide to peracid ratio are similarly
advantageous and suitable for use according to the invention,
including those disclosed in U.S. Provisional Patent Application
Ser. No. 61/710,631, filed Oct. 5, 2012, and entitled "Stable
Peroxycarboxylic Acid Compositions and Uses Thereof," and the
conversion application Ser. No. 13/844,515, which are herein
incorporated by reference in their entirety. These may include, for
example, equilibrium peracid compositions distilled to recover a
very low hydrogen peroxide peracid mixture, other catalysts for
hydrogen peroxide decomposition (e.g. biomimetic complexes) and/or
the use of perhydrolysis of peracid precursors, such as esters
(e.g. triacetin) and amides with alkyl leaving groups ranging in
carbon chain lengths of C1-C8, to obtain peracids with very low
hydrogen peroxide.
[0065] Compositions
[0066] The compositions of the invention may comprise, consist of
and/or consist essentially of a peracid composition having a low
hydrogen peroxide to peracid ratio. In an aspect, the peracid
composition has a hydrogen peroxide to peracid ratio in a
concentrated composition from about 0:100 to about 1:10, preferably
from about 0.5:100 to about 1:100, and more preferably from about
1:100 to 1:10. The compositions of the invention may comprise,
consist of and/or consist essentially of a peracid composition and
a peroxide-reducing agent used to obtain a resultant peracid
composition having a low hydrogen peroxide to peracid ratio. In
equilibrium chemistries there is a dynamic equilibrium between
peracids, respective carboxylic acids, hydrogen peroxide and water
in a composition. For example, a peracetic acid composition further
includes acetic acid, hydrogen peroxide and water in the aqueous
commercial formulation. Accordingly, the compositions of the
invention may further comprise, consist of and/or consist
essentially of a peracid composition, carboxylic acid, hydrogen
peroxide, and a peroxide-reducing enzyme. In other aspects,
additional functional ingredients, such as a friction reducer,
corrosion inhibitor, viscosity enhancer and/or additional
antimicrobial agent are employed in the compositions. In other
aspects, no additional functional ingredients are employed in the
compositions.
[0067] Peroxide-Reducing Agents
[0068] In an aspect of the invention, a peroxide-reducing agent is
used to reduce and/or eliminate the concentration of hydrogen
peroxide in an antimicrobial peracid composition. In some aspects,
the peroxide-reducing agent is a peroxide-reducing inorganic agent.
In an aspect of the invention, the agent is a metal and/or a strong
oxidizing agent. The metal catalyzes the decomposition of hydrogen
peroxide to water and oxygen. Further, the metal catalyzes the
decomposition of the peracid in equilibrium. Without being limited
to a particular mechanism of the invention, the decomposition of
the hydrogen peroxide and peracid of an equilibrium peracid
composition catalyzed by the peroxide-reducing agent beneficially
results in an accelerated oxidation reaction causing increased or
enhanced antimicrobial efficacy.
[0069] Beneficially, the reduction and/or elimination of hydrogen
peroxide (e.g. an oxidizer) further results in other additives for
a water treatment source (e.g. water source) not being degraded or
rendered incompatible. This is critical as various additives used
to enhance and/or modify the characteristics of aqueous fluids used
in well drilling, recovery and/or production applications are at
risk of degradation by the oxidizing effects of hydrogen peroxide.
These may include for example, friction reducers, scale inhibitors
and viscosity enhancers used in commercial well drilling, well
completion and stimulation, or production applications. According
to an aspect of the invention, the significant reduction in
hydrogen peroxide from a peracid composition reduces or eliminates
these compatibility and/or degradation concerns.
[0070] In an aspect, the peroxide-reducing agent is a metal,
combination of metals and/or a metal compound. Examples of suitable
metals for use as the peroxide-reducing agents (e.g. decomposition
agents) include heavy metals. In a further aspect, metal oxides may
be employed according to the invention. For example, suitable
metals include platinum, palladium, bismuth, tin, copper,
manganese, iron, tungsten, zirconium, ruthenium, cobalt,
molybdenum, nickel, iron, copper and/or manganese. In a preferred
aspect, the metals include platinum, tungsten, zirconium,
ruthenium, cobalt, molybdenum, nickel, iron, copper and/or
manganese. In a further preferred aspect of use in field operations
for well drilling, recovery and/or production applications, the
metals include iron, copper and/or manganese. In further aspects of
the invention, a combination of metals can be employed as the
peroxide-reducing agent.
[0071] In an aspect, the peroxide-reducing agent is a strong
oxidizer. Without being limited to a particular mechanism of action
of the compositions and/or methods of the invention, the oxidizer
has greater oxidizing potential that hydrogen peroxide,
beneficially allowing the decomposition of the oxidant hydrogen
peroxide. Examples of suitable strong oxidizers for use as
peroxide-reducing agents include halide anions, halide salts and/or
halide sources, including for example bromide and/or bromine,
iodide and/or iodine, chloride and/or chlorine, fluoride and/or
fluorine, etc. In a particular aspect, the peroxide-reducing agent
is a chlorine sources, including, for example, hypochlorite or
sodium hypochlorite, chlorine dioxide, or the like.
[0072] In a further aspect of the invention, the agent is not
UV-sensitive. In a further aspect of the invention, the metals
and/or strong oxidizing agents have a high ability to decompose
hydrogen peroxide. In some aspects, the peroxide-reducing agents
are able to degrade at least about 500 ppm of hydrogen peroxide in
a peracid composition in 15 minutes. In other aspects, the metals
and/or strong oxidizing agents also have a high ability to
decompose hydrogen peroxide at low concentrations. In some
embodiments, the concentration of metals and/or strong oxidizing
agents needed to degrade 500 ppm of hydrogen peroxide in a peracid
composition in 15 minutes is less than 200 ppm, less than 100 ppm,
and less than 50 ppm.
[0073] Beneficially, the reduction or elimination of hydrogen
peroxide from oxidizing compositions obviate the various detriments
caused by oxidizing agents in the various field operations for well
drilling, recovery and/or production applications (and others set
forth according to the methods of the invention). In particular,
the use of the peroxide-reducing agents) with the peracid
compositions provides enhanced antimicrobial benefits without
causing the damage associated with conventional oxidizing agents
(e.g. peracetic acid, hypochlorite or hypochlorous acid, and/or
chlorine dioxide), such as corrosion. In a further aspect, the
reduction of hydrogen peroxide also benefits the stability of gel
formation in gel frac fluids. Without being limited to a mechanism
of the invention, the reduction of hydrogen peroxide in a peracid
composition beneficially allows a gel frac fluid to maintain the
gel for a sufficient period of time (before it breaks apart within
the subterranean environment). In some aspects, the reduction of
the hydrogen peroxide within a peracid composition according to the
invention provides a suitable level of peroxide from about 1 ppm to
about 50 ppm, from about 1 ppm to about 25 ppm, or preferably from
about 5 ppm to about 15 ppm to maintain a stable gel frac fluid for
an extended period of time.
[0074] In an aspect, the peroxide-reducing agents preferentially
decompose hydrogen peroxide from a peracid composition (e.g. a
greater percentage of peracid concentration remains in a treated
peracid composition in comparison to hydrogen peroxide). Without
limiting the scope of peroxide-reducing agents suitable for use
according to the invention, in an aspect the agent preferentially
reduces hydrogen peroxide over the peracid. In a further aspect,
the agent reduces at least about 2:1 hydrogen peroxide to peracid,
or greater. In a further aspect, the agent reduces at least about
1.5:1 hydrogen peroxide to peracid, or greater.
[0075] In some embodiments, the peroxide-reducing agent is able to
degrade at least about 50% of the initial concentration of hydrogen
peroxide in a peracid composition. Preferably, the agent is
provided in sufficient amount to reduce the hydrogen peroxide
concentration of a peracid composition by at least more than about
50%, more preferably at least about 60%, at least about 70%, at
least about 80%, or at least about 90%. In some embodiments, the
peroxide-reducing agent reduces the hydrogen peroxide concentration
of a peracid composition by more than about 90%. Without limiting
the scope of invention, the numeric ranges are inclusive of the
numbers defining the range and include each integer within the
defined range.
[0076] In an aspect of the invention, the peroxide-reducing agents
are suitable for use and have a tolerance to a wide range of
temperatures, including the temperatures ranges in water treatment
applications which may range from about 0-180.degree. C. Although
temperature and other ambient conditions may affect the stability
of the agents, a suitable peroxide-reducing agent will maintain at
least 50% of its activity under such storage and/or application
temperatures for at least about 10 minutes, preferably for at least
about 1 hour, and more preferably for at least about 24 hours.
Without limiting the scope of invention, the numeric ranges are
inclusive of the numbers defining the range and include each
integer within the defined range.
[0077] In a further aspect of the invention, the peroxide-reducing
agents described herein have a tolerance to pH ranges found in
water treatment applications. Acetic acid levels (or other
carboxylic acid) in a water treatment application can widely range
in parts per million (ppm) of acetic or other carboxylic acid. The
solutions will have a corresponding range of pH range from greater
than 0 to about 10. A suitable peroxide-reducing agent will
maintain at least about 50% of its activity in such solutions of
acetic or other carboxylic acid over a period of about 10 minutes,
preferably for at least about 1 hour, and more preferably for at
least about 24 hours. Without limiting the scope of invention, the
numeric ranges are inclusive of the numbers defining the range and
include each integer within the defined range.
[0078] In an aspect of the invention, a peroxide-reducing agent is
present in a use solution of the water treatment and peracid
composition in sufficient amounts to reduce the concentration of
hydrogen peroxide from the peracid composition within at least a
few hours, preferably within less than 10 hours, preferably within
less than 5 hours, preferably within less than 4 hours, and still
more preferably within less than 1 hour. In an aspect of the
invention, a peroxide-reducing agent is present in a use solution
of the water treatment and peracid composition in sufficient
amounts to reduce the concentration of hydrogen peroxide from the
peracid composition by at least 50% within about 10 minutes,
preferably within about 5 minutes, preferably within about 2 to 5
minutes, more preferably within about 1 minute. The ranges of
concentration of the agents will vary depending upon the amount of
time within which 50% of the hydrogen peroxide from the peracid
composition is removed.
[0079] In certain aspects of the invention, a peroxide-reducing
agent is present in a use solution composition including the water
source to be treated in amounts of at least about 0.5 ppm,
preferably between about 0.5 ppm and about 1000 ppm, preferably
between about 0.5 ppm and about 500 ppm, preferably between about
0.5 ppm and 100 ppm, and more preferably between about 1 ppm and
about 100 ppm. Without limiting the scope of invention, the numeric
ranges are inclusive of the numbers defining the range and include
each integer within the defined range.
[0080] The peroxide-reducing agents employed may be free floating
in the use solution composition, meaning that the agent is part of
the composition, without being bound to a surface.
[0081] Alternatively, the peroxide-reducing agents may be
immobilized on a surface that is in fluid communication with the
use solution composition in way that allows the agent to interact
with and decompose hydrogen peroxide from the peracid compositions.
In some aspects, immobilized agents may be more stable than
unbound, soluble agents. In some aspects, immobilized agents may
also have increased thermal and pH stability which might be due to
the protection of the substrate provides against sudden thermal and
pH changes. An immobilized agent also has the advantage of being
able to be removed from the rest of the composition easily. An
immobilized agent may include an agent attached to a substrate.
Examples of substrates may include for example zeolites,
polyurethane foams, polyacrylamide gels, polyethylene maleic
anhydride gels, polystyrene maleic anhydride gels, cellulose,
nitrocellulose, silastic resins, porous glass, macroporous glass
membranes, glass beads, activated clay, zeolites, alumina, silica,
silicate and other inorganic and organic substrates. The
peroxide-reducing agent may be attached to the substrate in various
ways including carrier covalent binding, crosslinking, physical
adsorption, ionic binding, and entrapping.
[0082] In an aspect, the peroxide-reducing agent is added into a
peracid use solution instead of a concentrated peracid composition.
Without being limited to a mechanism of action, the use of a
peroxide-reducing agent is preferably added to a non-concentrated
peracid composition in order to maintain the viability and
peroxide-reducing capability of the agent. For example, in an
aspect, a concentrated peracid composition (e.g. about 10 wt-% or
greater peracid, or about 15 wt-% or greater peracid) is diluted
into a water source and thereafter the peroxide-reducing agent is
added. In an aspect, the dilute water source may be the water
source in need of treatment according to the invention. In another
aspect, the dilute water source may be a use solution of the
peracid composition (or less concentrated peracid composition) for
subsequent dosing into the water source in need of treatment
according to the invention.
[0083] Peroxide-Reducing Enzymes
[0084] In some aspects, the peroxide-reducing agent is a
peroxide-reducing enzyme. In an aspect of the invention, a catalase
or peroxidase enzyme is used to reduce and/or eliminate the
concentration of hydrogen peroxide in an antimicrobial peracid
composition. The enzymes catalyze the decomposition of hydrogen
peroxide to water and oxygen. Beneficially, the reduction and/or
elimination of hydrogen peroxide (strong oxidizer) results in other
additives for a water treatment source (e.g. water source) not
being degraded or rendered incompatible. Various additives used to
enhance or modify the characteristics of the aqueous fluids used in
well drilling, recovery and production applications are at risk of
degradation by the oxidizing effects of hydrogen peroxide. These
may include for example, friction reducers, scale inhibitors and
viscosity enhancers used in commercial well drilling, well
completion and stimulation, or production applications.
[0085] Various sources of catalase enzymes (or other
peroxide-reducing enzyme agents) may be employed according to the
invention, including: animal sources such as bovine catalase
isolated from beef livers; fungal catalases isolated from fungi
including Penicillium chrysogenum, Penicillium notatum, and
Aspergillus niger; plant sources; bacterial sources such as
Staphylcoccus aureus, and genetic variations and modifications
thereof. In an aspect of the invention, fungal catalases are
utilized to reduce the hydrogen peroxide content of a peracid
composition.
[0086] Catalases (or other peroxide-reducing enzyme agents) are
commercially available in various forms, including liquid and spray
dried forms. Commercially available catalase includes both the
active enzyme as well as additional ingredients to enhance the
stability of the enzyme. Some exemplary commercially available
catalase enzymes include Genencor CA-100 and CA-400, as well as
Mitsubishi Gas and Chemical (MGC) ASC super G and ASC super 200.
Additional description of suitable catalase enzymes are disclosed
and herein incorporated by reference in its entirety from U.S.
Patent Publication No. 2012/0321510 and U.S. Pat. Nos. 8,241,624,
8,231,917 and 8,226,939, which are herein incorporated by reference
in their entirety.
[0087] In an aspect of the invention, catalase enzymes (or other
peroxide-reducing enzyme agents) have a high ability to decompose
hydrogen peroxide. In some aspects, catalase enzymes (or other
peroxide-reducing enzyme agents) used in this invention include
enzymes with a high ability to decompose hydrogen peroxide. In some
embodiments, the enzyme is able to degrade at least about 500 ppm
of hydrogen peroxide in a peracid composition in 15 minutes. In
other aspects, enzymes used in this invention include catalase
enzymes (or other peroxide-reducing enzyme agents) with a high
ability to decompose hydrogen peroxide at low concentrations. In
some embodiments, the concentration of enzyme needed to degrade 500
ppm of hydrogen peroxide in a peracid composition in 15 minutes is
less than 200 ppm, less than 100 ppm, and less than 50 ppm.
[0088] Beneficially, the reduction or elimination of hydrogen
peroxide from oxidizing compositions obviates the various
detriments caused by oxidizing agents. In particular, the use of
catalase (or other peroxide-reducing enzyme agents) with the
peracids compositions provides enhanced antimicrobial benefits
without causing the damage associated with conventional oxidizing
agents (e.g. peracetic acid, hypochlorite or hypochlorous acid,
and/or chlorine dioxide), such as corrosion.
[0089] Peroxidase enzymes (or other peroxide-reducing enzyme
agents) may also be employed to decompose hydrogen peroxide from a
peracid composition. Although peroxidase enzymes primarily function
to enable oxidation of substrates by hydrogen peroxide, they are
also suitable for effectively lowering hydrogen peroxide to peracid
ratios in compositions. Various sources of peroxidase enzymes (or
other peroxide-reducing enzyme agents) may be employed according to
the invention, including for example animal sources, fungal
peroxidases, and genetic variations and modifications thereof.
Peroxidases are commercially available in various forms, including
liquid and spray dried forms. Commercially available peroxidases
include both the active enzyme as well as additional ingredients to
enhance the stability of the enzyme.
[0090] In some embodiments, the peroxide-reducing enzyme is able to
degrade at least about 50% of the initial concentration of hydrogen
peroxide in a peracid composition. Preferably, the enzyme is
provided in sufficient amount to reduce the hydrogen peroxide
concentration of a peracid composition by at least more than about
50%, more preferably at least about 60%, at least about 70%, at
least about 80%, at least about 90%. In some embodiments, the
enzyme reduces the hydrogen peroxide concentration of a peracid
composition by more than 90%. Without limiting the scope of
invention, the numeric ranges are inclusive of the numbers defining
the range and include each integer within the defined range.
[0091] In an aspect of the invention, the peroxide-reducing enzymes
are suitable for use and have a tolerance to a wide range of
temperatures, including the temperatures ranges in water treatment
applications which may range from about 0-180.degree. C. Although
temperature and other ambient conditions may affect the stability
of the enzymes, a suitable peroxide-reducing enzyme will maintain
at least 50% of its activity under such storage and/or application
temperatures for at least about 10 minutes, preferably for at least
about 1 hour, and more preferably for at least about 24 hours.
Without limiting the scope of invention, the numeric ranges are
inclusive of the numbers defining the range and include each
integer within the defined range.
[0092] In a further aspect of the invention, the peroxide-reducing
enzymes described herein have a tolerance to pH ranges found in
water treatment applications. Acetic acid levels (or other
carboxylic acid) in a water treatment application can widely range
in parts per million (ppm) of acetic or other carboxylic acid. The
solutions will have a corresponding range of pH range from greater
than 0 to about 10. A suitable peroxide-reducing enzyme will
maintain at least about 50% of its activity in such solutions of
acetic or other carboxylic acid over a period of about 10 minutes,
preferably for at least about 1 hour, and more preferably for at
least about 24 hours. Without limiting the scope of invention, the
numeric ranges are inclusive of the numbers defining the range and
include each integer within the defined range.
[0093] In an aspect of the invention, a peroxide-reducing enzyme is
present in a use solution of the water treatment and peracid
composition in sufficient amounts to reduce the concentration of
hydrogen peroxide from the peracid composition to sufficiently
reduced or eliminated concentration within at least a few hours,
preferably within less than 10 hours, preferably within less than 5
hours, preferably within less than 4 hours, and still more
preferably within less than 1 hour. In an aspect of the invention,
a peroxide-reducing enzyme is present in a use solution of the
water treatment and peracid composition in sufficient amounts to
reduce the concentration of hydrogen peroxide from the peracid
composition by at least 50% within about 10 minutes, preferably
within about 5 minutes, preferably within about 2 to 5 minutes,
more preferably within about 1 minute. The ranges of concentration
of the enzymes will vary depending upon the amount of time within
which 50% of the hydrogen peroxide from the peracid composition is
removed.
[0094] In certain aspects of the invention, a peroxide-reducing
enzyme is present in a use solution composition including the water
source to be treated in amounts of at least about 0.5 ppm,
preferably between about 0.5 ppm and about 1000 ppm, preferably
between about 0.5 ppm and about 500 ppm, preferably between about
0.5 ppm and 100 ppm, and more preferably between about 1 ppm and
about 100 ppm. Without limiting the scope of invention, the numeric
ranges are inclusive of the numbers defining the range and include
each integer within the defined range.
[0095] The enzymes employed may be free floating in the use
solution composition, meaning that the enzyme is part of the
composition, without being bound to a surface.
[0096] Alternatively, the enzymes may be immobilized on a surface
that is in fluid communication with the use solution composition in
way that allows the enzyme to interact with and decompose hydrogen
peroxide from the peracid compositions. Immobilized enzyme may be
more stable than unbound, soluble enzyme. Immobilized enzyme also
shows increased thermal and pH stability which might be due to the
protection of the substrate provides against sudden thermal and pH
changes. An immobilized enzyme also has the advantage of being able
to be removed from the rest of the composition easily. An
immobilized enzyme may include a soluble enzyme that is attached to
a substrate. Examples of substrates may include polyurethane foams,
polyacrylamide gels, polyethylene maleic anhydride gels,
polystyrene maleic anhydride gels, cellulose, nitrocellulose,
silastic resins, porous glass, macroporous glass membranes, glass
beads, activated clay, zeolites, alumina, silica, silicate and
other inorganic and organic substrates. The enzyme may be attached
to the substrate in various ways including carrier covalent
binding, crosslinking, physical adsorption, ionic binding, and
entrapping.
[0097] In an aspect, the peroxide-reducing enzyme is added into a
peracid use solution instead of a concentrated peracid composition.
Without being limited to a mechanism of action, the use of a
peroxide-reducing enzyme agent is preferably added to a
non-concentrated peracid composition in order to maintain the
viability and peroxide-reducing capability of the agent. For
example, in an aspect, a concentrated peracid composition (e.g.
about 10 wt-% or greater peracid, or about 15 wt-% or greater
peracid) is diluted into a water source and thereafter the
peroxide-reducing enzyme agent is added. In an aspect, the dilute
water source may be the water source in need of treatment according
to the invention. In another aspect, the dilute water source may be
a use solution of the peracid composition (or less concentrated
peracid composition) for subsequent dosing into the water source in
need of treatment according to the invention.
[0098] Peracids
[0099] In some aspects, a peracid is included for antimicrobial
efficacy in the compositions for water treatment. As used herein,
the term "peracid" may also be referred to as a "percarboxylic
acid" or "peroxyacid." Sulfoperoxycarboxylic acids, sulfonated
peracids and sulfonated peroxycarboxylic acids are also included
within the term "peracid" as used herein. The terms
"sulfoperoxycarboxylic acid," "sulfonated peracid," or "sulfonated
peroxycarboxylic acid" refers to the peroxycarboxylic acid form of
a sulfonated carboxylic acid as disclosed in U.S. Pat. No.
8,344,026, and U.S. Patent Publication Nos. 2010/0048730 and
2012/0052134, each of which are incorporated herein by reference in
their entirety. As one of skill in the art appreciates, a peracid
refers to an acid having the hydrogen of the hydroxyl group in
carboxylic acid replaced by a hydroxy group. Oxidizing peracids may
also be referred to herein as peroxycarboxylic acids.
[0100] A peracid includes any compound of the formula
R--(COOOH).sub.n in which R can be hydrogen, alkyl, alkenyl,
alkyne, acylic, alicyclic group, aryl, heteroaryl, or heterocyclic
group, and n is 1, 2, or 3, and named by prefixing the parent acid
with peroxy. Preferably R includes hydrogen, alkyl, or alkenyl. The
terms "alkyl," "alkenyl," "alkyne," "acylic," "alicyclic group,"
"aryl," "heteroaryl," and "heterocyclic group" are as defined
herein.
[0101] As used herein, the term "alkyl" includes a straight or
branched saturated aliphatic hydrocarbon chain having from 1 to 22
carbon atoms, such as, for example, methyl, ethyl, propyl,
isopropyl (1-methylethyl), butyl, tert-butyl (1,1-dimethylethyl),
and the like. The term "alkyl" or "alkyl groups" also refers to
saturated hydrocarbons having one or more carbon atoms, including
straight-chain alkyl groups (e.g., methyl, ethyl, propyl, butyl,
pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.), cyclic alkyl
groups (or "cycloalkyl" or "alicyclic" or "carbocyclic" groups)
(e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl,
cyclooctyl, etc.), branched-chain alkyl groups (e.g., isopropyl,
tert-butyl, sec-butyl, isobutyl, etc.), and alkyl-substituted alkyl
groups (e.g., alkyl-substituted cycloalkyl groups and
cycloalkyl-substituted alkyl groups).
[0102] Unless otherwise specified, the term "alkyl" includes both
"unsubstituted alkyls" and "substituted alkyls." As used herein,
the term "substituted alkyls" refers to alkyl groups having
substituents replacing one or more hydrogens on one or more carbons
of the hydrocarbon backbone. Such substituents may include, for
example, alkenyl, alkynyl, halogeno, hydroxyl, alkylcarbonyloxy,
arylcarbonyloxy, alkoxycarbonyloxy, aryloxy, aryloxycarbonyloxy,
carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl,
aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl,
alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato,
cyano, amino (including alkyl amino, dialkylamino, arylamino,
diarylamino, and alkylarylamino), acylamino (including
alkylcarbonylamino, arylcarbonylamino, carbamoyl and ureido),
imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfates,
alkylsulfinyl, sulfonates, sulfamoyl, sulfonamido, nitro,
trifluoromethyl, cyano, azido, heterocyclic, alkylaryl, or aromatic
(including heteroaromatic) groups.
[0103] The term "alkenyl" includes an unsaturated aliphatic
hydrocarbon chain having from 2 to 12 carbon atoms, such as, for
example, ethenyl, 1-propenyl, 2-propenyl, 1-butenyl,
2-methyl-1-propenyl, and the like. The alkyl or alkenyl can be
terminally substituted with a heteroatom, such as, for example, a
nitrogen, sulfur, or oxygen atom, forming an aminoalkyl, oxyalkyl,
or thioalkyl, for example, aminomethyl, thioethyl, oxypropyl, and
the like. Similarly, the above alkyl or alkenyl can be interrupted
in the chain by a heteroatom forming an alkylaminoalkyl,
alkylthioalkyl, or alkoxyalkyl, for example, methylaminoethyl,
ethylthiopropyl, methoxymethyl, and the like.
[0104] Further, as used herein the term "alicyclic" includes any
cyclic hydrocarbyl containing from 3 to 8 carbon atoms. Examples of
suitable alicyclic groups include cyclopropanyl, cyclobutanyl,
cyclopentanyl, etc. The term "heterocyclic" includes any closed
ring structures analogous to carbocyclic groups in which one or
more of the carbon atoms in the ring is an element other than
carbon (heteroatom), for example, a nitrogen, sulfur, or oxygen
atom. Heterocyclic groups may be saturated or unsaturated. Examples
of suitable heterocyclic groups include for example, aziridine,
ethylene oxide (epoxides, oxiranes), thiirane (episulfides),
dioxirane, azetidine, oxetane, thietane, dioxetane, dithietane,
dithiete, azolidine, pyrrolidine, pyrroline, oxolane, dihydrofuran,
and furan. Additional examples of suitable heterocyclic groups
include groups derived from tetrahydrofurans, furans, thiophenes,
pyrrolidines, piperidines, pyridines, pyrrols, picoline, coumaline,
etc.
[0105] According to the invention, alkyl, alkenyl, alicyclic
groups, and heterocyclic groups can be unsubstituted or substituted
by, for example, aryl, heteroaryl, C.sub.1-4 alkyl, C.sub.1-4
alkenyl, C.sub.1-4 alkoxy, amino, carboxy, halo, nitro, cyano,
--SO.sub.3H, phosphono, or hydroxy. When alkyl, alkenyl, alicyclic
group, or heterocyclic group is substituted, preferably the
substitution is C.sub.1-4 alkyl, halo, nitro, amido, hydroxy,
carboxy, sulpho, or phosphono. In one embodiment, R includes alkyl
substituted with hydroxy. The term "aryl" includes aromatic
hydrocarbyl, including fused aromatic rings, such as, for example,
phenyl and naphthyl. The term "heteroaryl" includes heterocyclic
aromatic derivatives having at least one heteroatom such as, for
example, nitrogen, oxygen, phosphorus, or sulfur, and includes, for
example, furyl, pyrrolyl, thienyl, oxazolyl, pyridyl, imidazolyl,
thiazolyl, isoxazolyl, pyrazolyl, isothiazolyl, etc. The term
"heteroaryl" also includes fused rings in which at least one ring
is aromatic, such as, for example, indolyl, purinyl, benzofuryl,
etc.
[0106] According to the invention, aryl and heteroaryl groups can
be unsubstituted or substituted on the ring by, for example, aryl,
heteroaryl, alkyl, alkenyl, alkoxy, amino, carboxy, halo, nitro,
cyano, --SO.sub.3H, phosphono, or hydroxy. When aryl, aralkyl, or
heteroaryl is substituted, preferably the substitution is C.sub.1-4
alkyl, halo, nitro, amido, hydroxy, carboxy, sulpho, or phosphono.
In one embodiment, R includes aryl substituted with C.sub.1-4
alkyl.
[0107] Peracids suitable for use include any peroxycarboxylic
acids, including varying lengths of peroxycarboxylic and
percarboxylic acids (e.g. C1-22) that can be prepared from the
acid-catalyzed equilibrium reaction between a carboxylic acid
described above and hydrogen peroxide. A peroxycarboxylic acid can
also be prepared by the auto-oxidation of aldehydes or by the
reaction of hydrogen peroxide with an acid chloride, acid hydride,
carboxylic acid anhydride, or sodium alcoholate. Alternatively,
peracids can be prepared through non-equilibrium reactions, which
may be generated for use in situ, such as the methods disclosed in
U.S. Patent Publication Nos. 2012/0172440 and 2012/0172441 each
titled "In Situ Generation of Peroxycarboxylic Acids at Alkaline
pH, and Methods of Use Thereof," which are incorporated herein by
reference in their entirety. Preferably a composition of the
invention includes peroxyacetic acid, peroxyoctanoic acid,
peroxypropionic acid, peroxylactic acid, peroxyheptanoic acid,
peroxyoctanoic acid and/or peroxynonanoic acid.
[0108] In some embodiments, a peroxycarboxylic acid includes at
least one water-soluble peroxycarboxylic acid in which R includes
alkyl of 1-22 carbon atoms. For example, in one embodiment, a
peroxycarboxylic acid includes peroxyacetic acid. In another
embodiment, a peroxycarboxylic acid has R that is an alkyl of 1-22
carbon atoms substituted with hydroxy. Methods of preparing
peroxyacetic acid are known to those of skill in the art including
those disclosed in U.S. Pat. No. 2,833,813, which is herein
incorporated herein by reference in its entirety.
[0109] In another embodiment, a sulfoperoxycarboxylic acid has the
following formula:
##STR00001##
wherein R.sub.1 is hydrogen, or a substituted or unsubstituted
alkyl group; R.sub.2 is a substituted or unsubstituted alkylene
group; X is hydrogen, a cationic group, or an ester forming moiety;
or salts or esters thereof. In some embodiments, R.sub.1 is a
substituted or unsubstituted C.sub.m alkyl group; X is hydrogen a
cationic group, or an ester forming moiety; R.sub.2 is a
substituted or unsubstituted C.sub.n alkyl group; m=1 to 10; n=1 to
10; and m+n is less than 18, or salts, esters or mixtures
thereof.
[0110] In some embodiments, R.sub.1 is hydrogen. In other
embodiments, R.sub.1 is a substituted or unsubstituted alkyl group.
In some embodiments, R.sub.1 is a substituted or unsubstituted
alkyl group that does not include a cyclic alkyl group. In some
embodiments, R.sub.1 is a substituted alkyl group. In some
embodiments, R.sub.1 is an unsubstituted C.sub.1-C.sub.9 alkyl
group. In some embodiments, R.sub.1 is an unsubstituted C.sub.7 or
C.sub.8 alkyl. In other embodiments, R.sub.1 is a substituted
C.sub.8-C.sub.10 alkylene group. In some embodiments, R.sub.1 is a
substituted C.sub.8-C.sub.10 alkyl group is substituted with at
least 1, or at least 2 hydroxyl groups. In still yet other
embodiments, R.sub.1 is a substituted C.sub.1-C.sub.9 alkyl group.
In some embodiments, R.sub.1 is a substituted C.sub.1-C.sub.9
substituted alkyl group is substituted with at least 1 SO.sub.3H
group. In other embodiments, R.sub.1 is a C.sub.9-C.sub.10
substituted alkyl group. In some embodiments, R.sub.1 is a
substituted C.sub.9-C.sub.10 alkyl group wherein at least two of
the carbons on the carbon backbone form a heterocyclic group. In
some embodiments, the heterocyclic group is an epoxide group.
[0111] In some embodiments, R.sub.2 is a substituted
C.sub.1-C.sub.10 alkylene group. In some embodiments, R.sub.2 is a
substituted C.sub.8-C.sub.10 alkylene. In some embodiments, R.sub.2
is an unsubstituted C.sub.6-C.sub.9 alkylene. In other embodiments,
R.sub.2 is a C.sub.8-C.sub.10 alkylene group substituted with at
least one hydroxyl group. In some embodiments, R.sub.2 is a
C.sub.10 alkylene group substituted with at least two hydroxyl
groups. In other embodiments, R.sub.2 is a C.sub.8 alkylene group
substituted with at least one SO.sub.3H group. In some embodiments,
R.sub.2 is a substituted C.sub.9 group, wherein at least two of the
carbons on the carbon backbone form a heterocyclic group. In some
embodiments, the heterocyclic group is an epoxide group. In some
embodiments, R.sub.1 is a C.sub.8-C.sub.9 substituted or
unsubstituted alkyl, and R.sub.2 is a C.sub.7-C.sub.8 substituted
or unsubstituted alkylene.
[0112] These and other suitable sulfoperoxycarboxylic acid
compounds for use in the stabilized peroxycarboxylic acid
compositions of the invention are further disclosed in U.S. Pat.
No. 8,344,026 and U.S. Patent Publication Nos. 2010/0048730 and
2012/0052134, which are incorporated herein by reference in its
entirety.
[0113] In additional embodiments a sulfoperoxycarboxylic acid is
combined with a single or mixed peroxycarboxylic acid composition,
such as a sulfoperoxycarboxylic acid with peroxyacetic acid,
peroxyoctanoic acid and sulfuric acid
(PSOA/POOA/POAA/H.sub.2SO.sub.4). In other embodiments, a mixed
peracid is employed, such as a peroxycarboxylic acid including at
least one peroxycarboxylic acid of limited water solubility in
which R includes alkyl of 5-22 carbon atoms and at least one
water-soluble peroxycarboxylic acid in which R includes alkyl of
1-4 carbon atoms. For example, in one embodiment, a
peroxycarboxylic acid includes peroxyacetic acid and at least one
other peroxycarboxylic acid such as those named above. Preferably a
composition of the invention includes peroxyacetic acid and
peroxyoctanoic acid. Other combinations of mixed peracids are well
suited for use in the current invention.
[0114] In another embodiment, a mixture of peracetic acid and
peroctanoic acid is used to treat a water source, such as disclosed
in U.S. Pat. No. 5,314,687 which is herein incorporated by
reference in its entirety. In an aspect, the peracid mixture is a
hydrophilic peracetic acid and a hydrophobic peroctanoic acid,
providing antimicrobial synergy. In an aspect, the synergy of a
mixed peracid system allows the use of lower dosages of the
peracids.
[0115] In another embodiment, a tertiary peracid mixture
composition, such as peroxysulfonated oleic acid, peracetic acid
and peroctanoic acid are used to treat a water source, such as
disclosed in U.S. Pat. No. 8,344,026 which is incorporated herein
by reference in its entirety. A combination of the three peracids
provides significant antimicrobial synergy providing an efficient
antimicrobial composition for the water treatment methods according
to the invention. In addition, it is thought the high acidity built
in the composition assists in removing chemical contaminants from
the water (e.g. sulfite and sulfide species), and the defoaming
agent (e.g. aluminum sulfate) provides defoaming (e.g. combating
foam caused by any anionic surface active agents used in the water
treatment).
[0116] Advantageously, a combination of peroxycarboxylic acids
provides a composition with desirable antimicrobial activity in the
presence of high organic soil loads. The mixed peroxycarboxylic
acid compositions often provide synergistic micro efficacy.
Accordingly, compositions of the invention can include a
peroxycarboxylic acid, or mixtures thereof.
[0117] Various commercial formulations of peracids are available,
including for example peracetic acid (15%) and hydrogen peroxide
(10%) available as EnviroSan (Ecolab, Inc., St. Paul Minn.). Most
commercial peracid solutions state a specific percarboxylic acid
concentration without reference to the other chemical components in
a use solution. However, it should be understood that commercial
products, such as peracetic acid, will also contain the
corresponding carboxylic acid (e.g. acetic acid), hydrogen peroxide
and water.
[0118] In an aspect, any suitable C.sub.1-C.sub.22 percarboxylic
acid can be used in the present compositions. In some embodiments,
the C.sub.1-C.sub.22 percarboxylic acid is a C.sub.2-C.sub.20
percarboxylic acid. In other embodiments, the C.sub.1-C.sub.22
percarboxylic is a C.sub.1, C.sub.2, C.sub.3, C.sub.4, C.sub.5,
C.sub.6, C.sub.7, C.sub.8, C.sub.9, C.sub.10, C.sub.11, C.sub.12,
C.sub.13, C.sub.14, C.sub.15, C.sub.16, C.sub.17, C.sub.18,
C.sub.19, C.sub.20, C.sub.21, or C.sub.22 carboxylic acid. In still
other embodiments, the C.sub.1-C.sub.22 percarboxylic acid
comprises peroxyacetic acid, peroxyoctanoic acid and/or
peroxysulfonated oleic acid.
[0119] In an aspect of the invention, a peracid is present in a use
solution with the water source in need of treatment in an amount of
between about 1 ppm and about 5000 ppm, preferably between about 1
ppm and about 2000 ppm, preferably between about 1 ppm and about
1000 ppm, and more preferably between about 1 ppm and about 100
ppm. Without limiting the scope of invention, the numeric ranges
are inclusive of the numbers defining the range and include each
integer within the defined range. The amount of peracid above the
preferred range of 100 ppm may be employed for highly contaminated
waters in need of treatment, such as source waters including
increased amounts of produced water (e.g. recycled waters).
[0120] In an aspect of the invention, a peracid may be selected
from a concentrated composition having a ratio of hydrogen peroxide
to peracid from about 0:100 to about 0.5:100, preferably from about
0.5:100 to about 1:10. Various concentrated peracid compositions
having the hydrogen peroxide to peracid ratios of about 0:100 to
about 0.5:100, preferably from about 0.5:100 to about 1:10 may be
employed to produce a use solution for treatment according to the
methods of the invention. In a further aspect of the invention, a
peracid may have a ratio of hydrogen peroxide to peracid as low as
from about 0.001 part or 0.01 part hydrogen peroxide to about 1
part peracid. Preferably, any ratio wherein the amount of hydrogen
peroxide is less than peracid is suitable for use according to the
invention in formulating a use solution for water treatments.
Without limiting the scope of invention, the numeric ranges are
inclusive of the numbers defining the range and include each
integer within the defined range.
[0121] Obtaining the preferred hydrogen peroxide to
peroxycarboxylic acid ratios in a peracid composition may be
obtained by a variety of methods suitable for producing a very low
hydrogen peroxide to peracid ratio. In an aspect, equilibrium
peracid compositions may be distilled to recover a very low
hydrogen peroxide peracid mixture. In yet another aspect, catalysts
for hydrogen peroxide decomposition may be combined with a peracid
composition, including for example, peroxide-reducing agents and/or
other biomimetic complexes. In yet another aspect, perhydrolysis of
peracid precursors, such as esters (e.g. triacetin) and amides may
be employed to obtain peracids with very low hydrogen peroxide.
[0122] In a particularly preferred aspect, the ester and amide
peracid precursors have alkyl leaving groups ranging in carbon
chain lengths of C1-C8. In each of these aspects, the
peroxycarboxylic acid concentration ranges from 0.0001 wt-% to 20
wt-%, preferably from about 0.0001 wt-% to 10 wt-%, or from about
0.0001 wt-% to 5 wt-%, or from about 1 wt-% to about 3 wt-%.
Without limiting the scope of invention, the numeric ranges are
inclusive of the numbers defining the range and include each
integer within the defined range.
[0123] In an aspect of the invention, a peroxide-reducing agent is
combined with a peracid composition. In an aspect, a peracid
composition having a concentration of less than or equal to about
10% may be combined with the peroxide-reducing agent, without
having a detrimental effect on the peroxide-reducing agent. In a
further preferred aspect, a peracid composition having a
concentration of less than or equal to about 5% is suitable for use
with the peroxide-reducing agent, without having a detrimental
effect on the peroxide-reducing agent. In a still further preferred
aspect, a peracid concentration of less than or equal to 3% is
preferred, or less than or equal to 2%. Without limiting the scope
of invention, the numeric ranges are inclusive of the numbers
defining the range and include each integer within the defined
range.
[0124] Hydrogen Peroxide
[0125] The present invention includes reduced amounts of hydrogen
peroxide, and preferably no hydrogen peroxide. Hydrogen peroxide,
H.sub.2O.sub.2, provides the advantages of having a high ratio of
active oxygen because of its low molecular weight (34.014 g/mole)
and being compatible with numerous substances that can be treated
by methods of the invention because it is a weakly acidic, clear,
and colorless liquid. Another advantage of hydrogen peroxide is
that it decomposes into water and oxygen. It is advantageous to
have these decomposition products because they are generally
compatible with substances being treated. For example, the
decomposition products are generally compatible with metallic
substance (e.g., substantially noncorrosive) and are generally
innocuous to incidental contact and are environmentally
friendly.
[0126] In one aspect of the invention, hydrogen peroxide is
initially in an antimicrobial peracid composition in an amount
effective for maintaining equilibrium between a carboxylic acid,
hydrogen peroxide, water and a peracid. The amount of hydrogen
peroxide should not exceed an amount that would adversely affect
the antimicrobial activity of a composition of the invention. In
further aspects of the invention, hydrogen peroxide concentration
is significantly reduced within an antimicrobial peracid
composition, preferably containing hydrogen peroxide at a
concentration as close to zero as possible. That is, the
concentration of hydrogen peroxide is minimized, through the use of
the selected peroxide-reducing agents according to the invention.
In further aspects, the concentration of hydrogen peroxide is
reduced and/or eliminated as a result of distilled equilibrium
peracid compositions, other catalysts for hydrogen peroxide
decomposition (e.g. biomimetic complexes) and/or the use of
perhydrolysis of esters (e.g. triacetin) to obtain peracids with
very low hydrogen peroxide.
[0127] According to the invention, an advantage of minimizing the
concentration of hydrogen peroxide is that antimicrobial activity
of a composition of the invention is improved as compared to
conventional equilibrium peracid compositions. Without being
limited to a particular theory of the invention, significant
improvements in antimicrobial efficacy result from enhanced
peracid, namely POAA stability from the reduced hydrogen peroxide
concentration.
[0128] In an aspect of the invention, hydrogen peroxide can
typically be present in a use solution in an amount less than 2500
ppm, preferably less than 2000 ppm, more preferably less than 1000
ppm. In preferred embodiments, the use of a catalase reduces the
hydrogen peroxide concentration as close to zero as possible,
preferably a concentration of zero. Without limiting the scope of
invention, the numeric ranges are inclusive of the numbers defining
the range and include each integer within the defined range.
[0129] In further aspects of the invention, hydrogen peroxide in a
peracid composition is reduced by at least 50%, at least 60%, at
least 70%, at least 80%, or at least 90%. Preferably the hydrogen
peroxide is substantially zero after the treatment of a peracid
composition according to the invention. In additional aspects, the
ratio of hydrogen peroxide to peracid in a concentrated composition
for use according to the invention is from about 0:100 to about
1:10, preferably from about 0.5:100 to about 0.5:10. Various
concentrated peracid compositions with a hydrogen peroxide to
peracid ratio from about 0:100 to about 1:10, preferably from about
0.5:100 to about 0.5:10, may be employed to produce a use solution
for treatment according to the invention. Without limiting the
scope of invention, the numeric ranges are inclusive of the numbers
defining the range and include each integer within the defined
range.
[0130] In a further aspect, a use solution may have a ratio of
hydrogen peroxide to peracid as low as from about 0.001 part
hydrogen peroxide to about 1 part peracid. Preferably, any ratio
wherein the amount of hydrogen peroxide is less than peracid is
suitable for use according to the invention in formulating a use
solution for water treatments. Without limiting the scope of
invention, the numeric ranges are inclusive of the numbers defining
the range and include each integer within the defined range.
[0131] Carboxylic Acid
[0132] The present invention includes a carboxylic acid with the
peracid composition and hydrogen peroxide. A carboxylic acid
includes any compound of the formula R--(COOH).sub.n in which R can
be hydrogen, alkyl, alkenyl, alkyne, acylic, alicyclic group, aryl,
heteroaryl, or heterocylic group, and n is 1, 2, or 3. Preferably R
includes hydrogen, alkyl, or alkenyl. The terms "alkyl," "alkenyl,"
"alkyne," "acylic," "alicyclic group," "aryl," "heteroaryl," and
"heterocyclic group" are as defined above with respect to
peracids.
[0133] Examples of suitable carboxylic acids according to the
equilibrium systems of peracids according to the invention include
a variety monocarboxylic acids, dicarboxylic acids, and
tricarboxylic acids. Monocarboxylic acids include, for example,
formic acid, acetic acid, propanoic acid, butanoic acid, pentanoic
acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid,
decanoic acid, undecanoic acid, dodecanoic acid, glycolic acid,
lactic acid, salicylic acid, acetylsalicylic acid, mandelic acid,
etc. Dicarboxylic acids include, for example, adipic acid, fumaric
acid, glutaric acid, maleic acid, succinic acid, malic acid,
tartaric acid, etc. Tricarboxylic acids include, for example,
citric acid, trimellitic acid, isocitric acid, agaicic acid,
etc.
[0134] In an aspect of the invention, a particularly well suited
carboxylic acid is water soluble such as formic acid, acetic acid,
propionic acid, butanoic acid, lactic acid, glycolic acid, citric
acid, mandelic acid, glutaric acid, maleic acid, malic acid, adipic
acid, succinic acid, tartaric acid, etc. Preferably a composition
of the invention includes acetic acid, octanoic acid, or propionic
acid, lactic acid, heptanoic acid, octanoic acid, or nonanoic acid.
Additional examples of suitable carboxylic acids are employed in
sulfoperoxycarboxylic acid or sulfonated peracid systems, which are
disclosed in U.S. Pat. No. 8,344,026, and U.S. Patent Publication
Nos. 2010/0048730 and 2012/0052134, each of which are herein
incorporated by reference in their entirety.
[0135] Any suitable C.sub.1-C.sub.22 carboxylic acid can be used in
the present compositions. In some embodiments, the C.sub.1-C.sub.22
carboxylic acid is a C.sub.2-C.sub.20 carboxylic acid. In other
embodiments, the C.sub.1-C.sub.22 carboxylic acid is a C.sub.1,
C.sub.2, C.sub.3, C.sub.4, C.sub.5, C.sub.6, C.sub.7, C.sub.8,
C.sub.9, C.sub.10, C.sub.11, C.sub.12, C.sub.13, C.sub.14,
C.sub.15, C.sub.16, C.sub.17, C.sub.18, C.sub.19, C.sub.20,
C.sub.21, or C.sub.22 carboxylic acid. In still other embodiments,
the C.sub.1-C.sub.22 carboxylic acid comprises acetic acid,
octanoic acid and/or sulfonated oleic acid.
[0136] In an aspect of the invention, a carboxylic acid is present
in a use solution with the water source in need of treatment in an
amount of between about 1 ppm and about 5000 ppm, preferably
between about 1 ppm and about 2000 ppm, preferably between about 1
ppm and about 1000 ppm, and more preferably between about 1 ppm and
about 100 ppm. Without limiting the scope of invention, the numeric
ranges are inclusive of the numbers defining the range and include
each integer within the defined range. The amount of carboxylic
acid above the preferred range of 100 ppm may be employed for
highly contaminated waters in need of treatment, such as source
waters including increased amounts of produced water (e.g. recycled
waters).
[0137] UV-Blocking Agent
[0138] The compositions according to the invention may further
include a UV-blocking and/or absorbing agent. In an aspect, a
UV-blocking agent is any agent that prevents and/or reduces the
amount of ultraviolet (UV) exposure of a water source in need of
treatment according to the invention. As set forth according to the
methods of the invention, in the alternative of a UV-blocking
agent, methods of use may be employed minimize and/or eliminate the
exposure to sunlight by dosing the peroxide-reducing agent at a
time with no and/or weak UV exposure is present, such as at night
and/or cloudy periods of time. However, one skilled in the art will
understand that reference to reducing and/or blocking UV according
to the invention will include either or both of these
scenarios.
[0139] In an aspect, the UV-blocking agent may include natural
(from a variety of sources) and/or synthetic dyes that are
compatible with the peracid compositions employed according to the
compositions and methods of the present invention. As referred to
herein, synthetic dyes include organic dyes, including for example
acid dyes and/or basic dyes. Preferably, the dyes are
water-soluble. In an aspect, the UV-blocking agents may include a
dye, a means of covering a water source, or the like, which are
suitable for decreasing and/or preventing the penetration of
sunlight into a water system in need of treatment. In an aspect,
dyes suitable for use as UV-blocking agents are those capable of
preventing and/or reducing the penetration of sunlight into a water
system.
[0140] In an aspect, the dye is a blue dye having considerable
absorption in the ultraviolet regions. In an exemplary embodiment,
the dye is for example, methylene blue (e.g. methylthioninium
chloride). In other aspects, the dye is a cationic dye. In other
aspects, the dye is a heterocyclic aromatic compound.
[0141] In a preferred aspect, the dye used as a UV-blocking agent
further has antimicrobial properties, such as the blue dye
methylene blue. In a still further preferred aspect, the dye used
as a UV-blocking agent further has anti-algae properties. Without
being limited to a particular mechanism of action and/or theory of
the invention, the UV-blocking agent in addition to preventing
and/or reducing the penetration of sunlight into a water system,
further provides the antimicrobial properties and/or anti-algae
properties which provide additional benefit(s) to the condition of
the water source, in addition to the benefit of allowing the
peroxide-reducing agent (e.g. catalase) to function to reduce the
hydrogen peroxide content in a use solution. Such additional
benefits provided to the water source through use of the
antimicrobial and/or anti-algae UV-blocking agent may prolong the
dosing frequency of the treated peracid composition.
[0142] In an aspect, the UV-blocking agent may be provided with
and/or formulated into a composition with the peroxide-reducing
agent according to the invention. In an alternative aspect, the
UV-blocking agent may be provided separately from both the peracid
composition and/or the peroxide-reducing agent. According to such
embodiments of the invention the UV-blocking agent may be
formulated into a two or three part component system for treating a
water source according to the methods of the invention.
[0143] In an aspect of the invention, UV-blocking agent is provided
in a use solution in an amount of from about 0.1 ppm to about 5000
ppm, preferably from about 1 ppm to about 2000 ppm, more preferably
from about 1 ppm to about 500 ppm. Without limiting the scope of
invention, the numeric ranges are inclusive of the numbers defining
the range and include each integer within the defined range.
[0144] Additional Optional Materials
[0145] The composition can optionally include additional
ingredients to enhance the composition for water treatment
according to the invention, including for example, friction
reducers, viscosity enhancers, UV-blocking agents and the like.
Additional optional functional ingredients may include for example,
peracid stabilizers, emulsifiers, corrosion inhibitors and/or
descaling agents (i.e. scale inhibitors), surfactants and/or
additional antimicrobial agents for enhanced efficacy (e.g. mixed
peracids, biocides), antifoaming agents, acidulants (e.g. strong
mineral acids) or other pH modifiers, additional carboxylic acids,
and the like. In an embodiment, no additional functional
ingredients are employed.
[0146] Friction Reducers
[0147] Friction reducers are used in water or other water-based
fluids used in hydraulic fracturing treatments for subterranean
well formations in order to improve permeability of the desired gas
and/or oil being recovered from the fluid-conductive cracks or
pathways created through the fracking process. The friction
reducers allow the water to be pumped into the formations more
quickly. Various polymer additives have been widely used as
friction reducers to enhance or modify the characteristics of the
aqueous fluids used in well drilling, recovery and production
applications.
[0148] Examples of commonly used friction reducers include
polyacrylamide polymers and copolymers. In an aspect, additional
suitable friction reducers may include acrylamide-derived polymers
and copolymers, such as polyacrylamide (sometime abbreviated as
PAM), acrylamide-acrylate (acrylic acid) copolymers, acrylic
acid-methacrylamide copolymers, partially hydrolyzed polyacrylamide
copolymers (PHPA), partially hydrolyzed polymethacrylamide,
acrylamide-methyl-propane sulfonate copolymers (AMPS) and the like.
Various derivatives of such polymers and copolymers, e.g.,
quaternary amine salts, hydrolyzed versions, and the like, should
be understood to be included with the polymers and copolymers
described herein.
[0149] Friction reducers are combined with water and/or other
aqueous fluids, which in combination are often referred to as
"slick water" fluids. Slick water fluids have reduced frictional
drag and beneficial flow characteristics which enable the pumping
of the aqueous fluids into various gas- and/or oil-producing areas,
including for example for fracturing.
[0150] In an aspect of the invention, a friction reducer is present
in a use solution in an amount between about 100 ppm to 1000 ppm.
In a further aspect, a friction reducer is present in a use
solution in an amount of at least about 0.01 wt-% to about 10 wt-%,
preferably at least about 0.01 wt-% to about 5 wt-%, preferably at
least about 0.01 wt-% to about 1 wt-%, more preferably at least
about 0.01 wt-% to about 0.5 wt-%, and still more preferably at
least about 0.01 wt-% to about 0.1 wt-%. Without limiting the scope
of invention, the numeric ranges are inclusive of the numbers
defining the range and include each integer within the defined
range.
[0151] Beneficially, the compositions and methods of the invention
do not negatively interfere with friction reducers included in an
aqueous solution. Without being limited to a particular theory of
the invention, it is thought that the reduction and/or elimination
of the oxidant hydrogen peroxide from the peracid composition
promotes the stability and efficacy of any variation in the amount
of friction reducer present in a use solution.
[0152] Viscosity Enhancers
[0153] Viscosity enhancers are additional polymers used in water or
other water-based fluids used in hydraulic fracturing treatments to
provide viscosity enhancement. Natural and/or synthetic
viscosity-increasing polymers may be employed in compositions and
methods according to the invention. Viscosity enhancers may also be
referred to as gelling agents and examples include guar, xanthan,
cellulose derivatives and polyacrylamide and polyacrylate polymers
and copolymers, and the like.
[0154] In an aspect of the invention, a viscosity enhancer is
present in a use solution in an amount between about 100 ppm to
1000 ppm. In a further aspect, a viscosity enhancer is present in a
use solution in an amount of at least about 0.01 wt-% to about 10
wt-%, preferably at least about 0.01 wt-% to about 5 wt-%,
preferably at least about 0.01 wt-% to about 1 wt-%, at least about
0.01 wt-% to about 2 wt-%, preferably at least about 0.01 wt-% to
about 1 wt-%, preferably at least about 0.01 wt-% to about 0.5
wt-%. Without limiting the scope of invention, the numeric ranges
are inclusive of the numbers defining the range and include each
integer within the defined range.
[0155] Beneficially, the compositions and methods of the invention
do not negatively interfere with viscosity enhancer included in an
aqueous solution. Without being limited to a particular theory of
the invention, it is believed the reduction and/or elimination of
the oxidant hydrogen peroxide from the peracid composition promotes
the stability and efficacy of any variation in the amount of
viscosity enhancer present in a use solution.
[0156] Corrosion Inhibitors
[0157] Corrosion inhibitors are additional molecules used in oil
and gas recovery operations. Corrosion inhibitors that may be
employed in the present disclosure are disclosed in U.S. Pat. No.
5,965,785, U.S. Patent Publication No. 2010/0108566, GB Patent No.
1,198,734, WO/03/006581, WO04/044266, and WO08/005058, each of
which are incorporated herein by reference in their entirety.
[0158] In an aspect of the invention, a corrosion inhibitor is
present in a use solution in an amount between about 100 ppm to
1000 ppm. In a further aspect, a corrosion inhibitor is present in
a use solution in an amount of at least about 0.0001 wt-% to about
10 wt-%, preferably at least about 0.0001 wt-% to about 5 wt-%,
preferably at least about 0.0001 wt-% to about 1 wt-%, preferably
at least about 0.0001 wt-% to about 0.1 wt-%, and still more
preferably at least about 0.0001 wt-% to about 0.05 wt-%. Without
limiting the scope of invention, the numeric ranges are inclusive
of the numbers defining the range and include each integer within
the defined range.
[0159] Beneficially, the compositions and methods of the invention
do not negatively interfere with corrosion inhibitor included in an
aqueous solution. Without being limited to a particular theory of
the invention, it is believed the reduction and/or elimination of
the oxidant hydrogen peroxide from the peracid composition promotes
the stability and efficacy of any variation in the amount of
corrosion inhibitor present in a use solution.
[0160] Scale Inhibitors
[0161] Scale inhibitors are additional molecules used in oil and
gas recovery operations. Common scale inhibitors that may be
employed in these types of applications include polymers and
co-polymers, phosphates, phosphate esters and the like.
[0162] In an aspect of the invention, a scale inhibitor is present
in a use solution in an amount between about 100 ppm to 1000 ppm.
In a further aspect, a scale inhibitor is present in a use solution
in an amount of at least about 0.0001 wt-% to about 10 wt-%, at
least about 0.0001 wt-% to about 1 wt-%, preferably at least about
0.0001 wt-% to about 0.1 wt-%, preferably at least about 0.0001
wt-% to about 0.05 wt-%. Without limiting the scope of invention,
the numeric ranges are inclusive of the numbers defining the range
and include each integer within the defined range.
[0163] Beneficially, the compositions and methods of the invention
do not negatively interfere with scale inhibitor included in an
aqueous solution. Without being limited to a particular theory of
the invention, it is thought that the reduction and/or elimination
of the oxidant hydrogen peroxide from the peracid composition
promote the stability and efficacy of any variation in the amount
of scale inhibitor present in a use solution.
[0164] Additional Antimicrobial Agents
[0165] Additional antimicrobial agents may be included in the
compositions and/or methods of the invention for enhanced
antimicrobial efficacy. In addition to the use of mixed peracid
compositions, additional antimicrobial agents (e.g. surfactants)
and biocides may be employed. Additional biocides may include, for
example, a quaternary ammonium compound as disclosed in U.S. Pat.
No. 6,627,657, which is incorporated herein by reference in its
entirety. Beneficially, the presence of the quaternary ammonium
compound provides both synergistic antimicrobial efficacies with
peracids, as well as maintains long term biocidal efficacy of the
compositions.
[0166] In another embodiment, the additional biocide may include an
oxidizer compatible phosphonium biocide, such as tributyl
tetradecyl phosphonium chloride. The phosphonium biocide provides
similar antimicrobial advantages as the quaternary ammonium
compound in combination with the peracids. In addition, the
phosphonium biocide is compatible with the anionic polymeric
chemicals commonly used in the oil field applications, such as the
methods of the fracking disclosed according to the invention.
[0167] Additional antimicrobial and biocide agents may be employed
in amounts sufficient to provide antimicrobial efficacy, as may
vary depending upon the water source in need of treatment and the
contaminants therein. Such agents may be present in a use solution
in an amount of at least about 0.1 wt-% to about 50 wt-%,
preferably at least about 0.1 wt-% to about 20 wt-%, more
preferably from about 0.1 wt-% to about 10 wt-%. Without limiting
the scope of invention, the numeric ranges are inclusive of the
numbers defining the range and include each integer within the
defined range.
[0168] Acidulants
[0169] Acidulants may be included as additional functional
ingredients in a composition according to the invention. In an
aspect, a strong, oxidative mineral acid such as nitric acid or
sulfuric acid can be used to treat water sources, as disclosed in
U.S. Pat. No. 4,587,264, which is incorporated herein by reference
in its entirety. For example, the combined use of a strong mineral
acid with the peracid composition provides enhanced antimicrobial
efficacy as a result of the acidity assisting in removing chemical
contaminants within the water source (e.g. sulfite and sulfide
species). In an aspect of the invention, the use of an acidulant,
such as a mineral acid, is suitable for decreasing the pH of the
water source and/or the treated peracid composition to obtain
additional and/or synergistic impact on cleaning efficacy.
[0170] In an aspect, an acidulant may be used to decrease the pH of
the water source in need of treatment to a pH below about 6,
preferably below about 5, and more preferably between about 4.5 and
about 5.5 to get a synergistic impact on water clean-up from the
acid. In a preferred aspect, an acidulant is used to decrease the
pH of the treated water source from about 2 to about 6 to provide a
synergistic impact on water clean-up. According to such an
embodiment, any acidulant may be employed to decrease the pH of the
water source. Examples of suitable acidulants include hydrochloric
acid and other acids, and chlorine, chlorine dioxide (ClO.sub.2)
and other oxidants.
[0171] In addition, some strong mineral acids, such as nitric acid,
provide a further benefit of reducing the risk of corrosion toward
metals contacted by the peracid compositions according to the
invention. Exemplary peracid products containing nitric acid are
commercially available from Enviro Tech Chemical Services, Inc.
(Reflex brand) and from Solvay Chemicals (Proxitane.RTM. NT
brand).
[0172] In a still further aspect, an acidulant may be employed to
decrease the pH of the peracid composition according to the
invention to increase the peracid stability by decreasing the pH of
the peracid composition. For example, in some embodiments
decreasing the pH of the treated peracid composition from about 8
or greater to less than about 8, or less than about 7.5, or less
than about 7 has a beneficial impact on the peracid stability for
use according to the methods of the invention.
[0173] Acidulants may be employed in amounts sufficient to provide
the intended antimicrobial efficacy, peracid stability and/or
anticorrosion benefits, as may vary depending upon the peracid
composition and/or water source in need of treatment and the
contaminants therein. Such agents may be present in a use solution
in an amount of at least about 0.1 wt-% to about 50 wt-%,
preferably at least about 0.1 wt-% to about 20 wt-%, more
preferably from about 0.1 wt-% to about 10 wt-%. Without limiting
the scope of invention, the numeric ranges are inclusive of the
numbers defining the range and include each integer within the
defined range.
[0174] Peracid Stabilizers
[0175] In some embodiments, the compositions of the present
invention include one or more stabilizing agents. The stabilizing
agents can be used, for example, to stabilize the peracid and
hydrogen peroxide and prevent the premature oxidation of this
constituent within the composition of the invention.
[0176] In some embodiments, an acidic stabilizing agent can be
used. Thus, in some embodiments, the compositions of the present
invention can be substantially free of an additional acidulant.
[0177] Suitable stabilizing agents include, for example, chelating
agents or sequestrants. Suitable sequestrants include, but are not
limited to, organic chelating compounds that sequester metal ions
in solution, particularly transition metal ions. Such sequestrants
include organic amino- or hydroxy-polyphosphonic acid complexing
agents (either in acid or soluble salt forms), carboxylic acids
(e.g., polymeric polycarboxylate), hydroxycarboxylic acids,
aminocarboxylic acids, or heterocyclic carboxylic acids, e.g.,
pyridine-2,6-dicarboxylic acid (dipicolinic acid).
[0178] In some embodiments, the compositions of the present
invention include dipicolinic acid as a stabilizing agent.
Compositions including dipicolinic acid can be formulated to be
free or substantially free of phosphorous.
[0179] In other embodiments, the sequestrant can be or include
phosphonic acid or phosphonate salt. Suitable phosphonic acids and
phosphonate salts include HEDP; ethylenediamine tetrakis
methylenephosphonic acid (EDTMP); diethylenetriamine pentakis
methylenephosphonic acid (DTPMP); cyclohexane-1,2-tetramethylene
phosphonic acid; amino[tri(methylene phosphonic acid)]; (ethylene
diamine[tetra methylene-phosphonic acid)]; 2-phosphene
butane-1,2,4-tricarboxylic acid; or salts thereof, such as the
alkali metal salts, ammonium salts, or alkyloyl amine salts, such
as mono, di, or tetra-ethanolamine salts; picolinic, dipicolinic
acid or mixtures thereof. In some embodiments, organic
phosphonates, e.g., HEDP are included in the compositions of the
present invention.
[0180] Commercially available food additive chelating agents
include phosphonates sold under the trade name DEQUEST.RTM.
including, for example, 1-hydroxyethylidene-1,1-diphosphonic acid,
available from Monsanto Industrial Chemicals Co., St. Louis, Mo.,
as DEQUEST.RTM. 2010; amino(tri(methylenephosphonic acid)),
(N[CH.sub.2PO.sub.3H.sub.2].sub.3), available from Monsanto as
DEQUEST.RTM. 2000; ethylenediaminc[tetra(methylenephosphonic acid)]
available from Monsanto as DEQUEST.RTM. 2041; and
2-phosphonobutane-1,2,4-tricarboxylic acid available from Mobay
Chemical Corporation, Inorganic Chemicals Division, Pittsburgh,
Pa., as Bayhibit AM.
[0181] The sequestrant can be or include aminocarboxylic acid type
sequestrant. Suitable aminocarboxylic acid type sequestrants
include the acids or alkali metal salts thereof, e.g., amino
acetates and salts thereof. Suitable aminocarboxylates include
N-hydroxyethylaminodiacetic acid; hydroxyethylenediaminetetraacetic
acid, nitrilotriacetic acid (NTA); ethylenediaminetetraacetic acid
(EDTA); N-hydroxyethyl-ethylenediaminetriacetic acid (HEDTA);
diethylenetriaminepentaacetic acid (DTPA); and alanine-N,N-diacetic
acid; and the like; and mixtures thereof.
[0182] The sequestrant can be or include a polycarboxylate.
Suitable polycarboxylates include, for example, polyacrylic acid,
maleic/olefin copolymer, acrylic/maleic copolymer, polymethacrylic
acid, acrylic acid-methacrylic acid copolymers, hydrolyzed
polyacrylamide, hydrolyzed polymethacrylamide, hydrolyzed
polyamide-methacrylamide copolymers, hydrolyzed polyacrylonitrile,
hydrolyzed polymethacrylonitrile, hydrolyzed
acrylonitrile-methacrylonitrile copolymers, polymaleic acid,
polyfumaric acid, copolymers of acrylic and itaconic acid,
phosphino polycarboxylate, acid or salt forms thereof, mixtures
thereof, and the like.
[0183] In certain embodiments, the present composition includes
about 0.01 to about 10 wt-% stabilizing agent, about 0.4 to about 4
wt-% stabilizing agent, about 0.6 to about 3 wt-% stabilizing
agent, about 1 to about 2 wt-% stabilizing agent. It is to be
understood that all values and ranges within these values and
ranges are encompassed by the present invention.
[0184] Methods of Use
[0185] In some aspects, the methods disclosed for water treatment
in oil and gas recovery provide effective antimicrobial efficacy
without any deleterious interaction with functional agents,
including for example friction reducers. In a further aspect, the
methods for water treatment according to the invention using the
peroxide-reducing agent provide increased antimicrobial efficacy
compared to the use of the antimicrobial peracids alone. In a still
further aspect, the methods of use result in the disposal of
cleaner water with low numbers of microorganisms. In yet a still
further aspect of the methods of the invention, the reduction
and/or elimination of H.sub.2O.sub.2 from the peracid compositions
minimizes the negative effects of the oxidant H.sub.2O.sub.2.
[0186] Use in Water Treatment
[0187] The treated peracid compositions (i.e. reduced or no
hydrogen peroxide peracid compositions) can be used for a variety
of industrial applications, e.g., to reduce microbial or viral
populations on a surface or object or in a body or stream of water.
In some aspects, the invention includes methods of using the
treated peracid compositions to prevent biological fouling in
various industrial processes and industries, including oil and gas
operations, to control microorganism growth, eliminate microbial
contamination, limit or prevent biological fouling in liquid
systems, process waters or on the surfaces of equipment that come
in contact with such liquid systems. As referred to herein,
microbial contamination can occur in various industrial liquid
systems including, but not limited to, air-borne contamination,
water make-up, process leaks and improperly cleaned equipment. In
another aspect, the peracid and peroxide-reducing enzyme agent
(e.g. catalase) compositions (or other treated peracid compositions
having low to substantially no hydrogen peroxide) are used to
control the growth of microorganisms in water used in various oil
and gas operations. In a further aspect, the compositions are
suitable for incorporating into fracturing fluids to control or
eliminate microorganisms.
[0188] As used herein for the methods of the invention, treated
peracid compositions can employ a variety of peracid compositions
having a low to substantially no hydrogen peroxide concentration.
These treated peracid compositions include peracid compositions
with a peroxide-reducing agent to reduce the hydrogen peroxide to
peracid ratio and/or other reduced hydrogen peroxide peracid
compositions disclosed herein. In a preferred embodiment, peracid
and peroxide-reducing agent use solutions having reduced or
substantially no hydrogen peroxide are introduced to a water source
in need of treatment.
[0189] The methods by which the treated peracid use solutions are
introduced into the aqueous fluids according to the invention are
not critical. Introduction of the treated peracid compositions
(and/or introduction of the two or more part system, such as a
peracid composition and a peroxide-reducing agent composition, may
be carried out in a continuous or intermittent manner and will
depend on the type of water being treated.
[0190] In an aspect, treated peracid use solutions are employed
according to the methods of the invention. As referred to herein,
treated peracid compositions or treated peracid use solutions are
understood to refer to peracid compositions having reduced or
substantially no hydrogen peroxide. Such reduced or substantially
no hydrogen peroxide peracid compositions may be generated by use
of peroxide-reducing agent(s) at a point of use (e.g. combining
more than one component part of the composition--e.g. the
peroxide-reducing agent and a peracid composition in a two part
system) and/or generated prior to a point of use.
[0191] In an aspect, the treated peracid compositions are generated
at a point of use, and may be generated within a water source on
site. In an aspect, the peracid composition and a peroxide-reducing
enzyme agent, such as a catalase enzyme, are combined with a water
source at a point of use and the hydrogen peroxide concentration of
the use solution is reduced within a period of time from at least a
minute to a few hours, preferably from at least 5 minutes to a few
hours. One skilled in the art will ascertain that the treatment
time for a use solution of a peracid composition within a water
source to be treated will vary depending upon the concentration of
the peroxide-reducing agent and/or the volume of the peracid
composition and/or water source in need of treatment. The
concentrations of the peracid composition and peroxide-reducing
agent will further vary depending upon the amount of bacteria
within the water source in need of treatment.
[0192] In an aspect, the treated peracid use solutions may further
comprise a UV-blocking agent and/or other means of minimizing
and/or preventing UV exposure of the treated peracid use solutions
and/or the water in need of treatment with the peracid
compositions. Without being limited to a particular theory or
mechanism of the invention, the use of UV-blocking agents (or other
means of minimizing and/or preventing UV exposure) allows for the
effective reduction of hydrogen peroxide concentration within a
peracid composition according to the invention.
[0193] In an aspect, a suitable UV-blocking agent is provided in a
peracid composition. Beneficially, the use of the disclosed
UV-blocking agents is stable for formulation within the peracid
compositions. In another aspect, the UV-blocking agent may be added
directly to a water source in need of treatment either
simultaneously with a peracid composition or in sequence with the
peracid compositions.
[0194] In still further aspects, the UV-blocking agent may
alternatively be replaced with methods of application of the
peracid compositions that effectively minimize the exposure to
sunlight (e.g. dosing the peroxide-reducing agent at a time with no
and/or weak sunlight, such as at night and/or cloudy periods of
time). In still other aspects, the UV-blocking agent may refer to a
cover that physically blocks sunlight from the water source.
[0195] In an aspect, the treated peracid use solutions are added to
waters in need of treatment prior to the drilling and fracking
steps in order to restrict the introduction of microbes into the
reservoir and to prevent the microbes from having a negative effect
on the integrity of the fluids. The treatment of source waters
(e.g. pond, holding tank, lake, municipal, etc.) and/or produced
waters is particularly well suited for use according to the
invention.
[0196] The treated waters according to the invention can be used
for both slick water fracturing (i.e. using frictions reducers)
and/or gel fracturing (i.e. using viscosity enhancers), depending
on the type of formation being fractured and the type of
hydrocarbon expected to be produced. Use of a treated peracid use
solution, namely a peroxide-reducing agent treated peracid
composition use solution having low to substantially no hydrogen
peroxide, is suitable for both slick water fracturing and gel
fracturing.
[0197] In an aspect, pretreating the peracid composition, such as
peracetic acid (including a mixture of acetic acid, hydrogen
peroxide and water) with a peroxide-reducing agent substantially
removes the hydrogen peroxide with minimal to no impact on the
fracturing fluids and the well itself. In an aspect, the peracetic
acid pretreated with a peroxide-reducing agent allows the formation
of gel suitable for gel fracturing, as opposed to untreated
peracetic acid/hydrogen peroxide solutions that do not allow a gel
to form. In a further aspect, the treated peracid use solutions are
added to waters in need of treatment in the subterranean well
formations (e.g. introduced through a bore hole in a subterranean
formation). These methods provide additional control within the
well formation suitable for reducing microbial populations already
present within the down hole tubing in the well or within the
reservoir itself.
[0198] In a still further aspect, the treated peracid use solutions
are added to waters in need of treatment before disposal. In such
an aspect, flow back waters (e.g. post fracking) are treated to
minimize microbial contaminations in the waters and to remove
solids prior to disposal of the water into a subterranean well,
reuse in a subsequent fracturing application or return of the water
into local environmental water sources.
[0199] In a still further aspect, the treated peracid use solutions
are added to waters in need of treatment before disposal. In such
an aspect, flow back waters (e.g. post fracking) are treated to
minimize microbial contaminations in the waters and to remove
solids prior to disposal of the water into a subterranean well,
reuse in a subsequent fracturing application or return of the water
into local environmental water sources.
[0200] In an alternative aspect, the treated peracid use solution
may be formed within the water source to be treated. For example, a
peracid composition is provided to a water source and a
peroxide-reducing agent is thereafter provided to the water source,
such that the reduction and/or elimination of peroxide
concentration occur within the water source. These methods provide
additional control within the well formation suitable for reducing
microbial populations already present within the down hole tubing
in the well or within the reservoir itself.
[0201] In an aspect of the invention, the methods of treating a
water source may include the cyclical dosing of treated (e.g. low
or no hydrogen peroxide) peracid compositions to a water source. In
an alternative aspect, the methods of treating a water source may
include the cyclical dosing of a water source with a two (or more)
part composition used to generate the treated (e.g. low or no
hydrogen peroxide) peracid composition within the water source in
need of treatment. Such cyclical dosing may include daily dosing,
every two or more day dosing, every three or more day dosing, every
four or more day dosing, every five or more day dosing, every six
or more day dosing, weekly dosing, or longer frequency dosing. In a
preferred aspect, the water source is treated in an every five day
cycle for optimal reduction or elimination of hydrogen peroxide
within a peracid composition used to treat the water source.
Without being limited according to the mechanism and/or the scope
of the invention, all ranges of the dosing cycles are included
within the scope of the invention. In an aspect, the present
invention is directed to a method for treating water, which method
comprises providing the above compositions to a water source in
need of treatment to form a treated water source, wherein said
treated water source comprises from about 1 ppm to about 1,000 ppm
of said C.sub.1-C.sub.22 percarboxylic acid. Any suitable
C.sub.1-C.sub.22 percarboxylic acid can be used in the present
methods. For example, peroxyacetic acid, peroxyoctanoic acid and/or
peroxysulfonated oleic acid can be used. In some embodiments, a
combination of peroxyacetic acid, peroxyoctanoic acid and
peroxysulfonated oleic acid is used.
[0202] The treated peracid composition provides a water source with
any suitable concentration of the hydrogen peroxide. In some
embodiments, the treated water source comprises from about 1 ppm to
about 15 ppm of the hydrogen peroxide. In other embodiments, the
treated water source comprises about 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5
ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 11 ppm, 12 ppm, 13 ppm, 14
ppm, or 15 ppm of the hydrogen peroxide.
[0203] In an aspect, the treated peracid use solutions may be added
to an incoming stream of water, such as water added to a holding
tank or other storage reservoir. In an embodiment, the treated
peracid use solutions are added to provide a peracid concentration
(e.g. peracetic acid) applied at a rate of about 1 ppm to about
5000 ppm peracid, from about 1 ppm to about 2000 ppm, from about 1
ppm to about 1000 ppm, from about 1 ppm to about 500 ppm, and
preferably from about 1 ppm to about 100 ppm peracid. Without being
limited according to the mechanism and/or the scope of the
invention, all ranges are included within the scope of the
invention.
[0204] In an alternative aspect, the treated peracid use solutions
may be added at an elevated peracid concentration (e.g. about 200
to about 5000 ppm) to an intermittent water source (e.g. a smaller
holding tank, such as up to about 1000 gallons of water) prior to
dilution within a larger holding tank or other storage reservoir
for a water source (e.g. 1 million gallons of water or more). Upon
such dilution within a larger water source the peracid becomes
quickly diluted to the preferred rate of about 0.1 ppm to about 100
ppm peracid, preferably from about 1 ppm to about 100 ppm peracid.
Without being limited to a mechanism of action, such a method
beneficially provides a rapid kill of microorganisms within a
controlled/smaller volume of a water source in need of treatment,
while still providing a static or slower antimicrobial activity
within a bulk water system.
[0205] In a still further alternative aspect, the treated peracid
use solutions may be added to a larger bulk fluid, such as the
holding tank or other storage reservoir for a water source. For
example, in some aspects, a bulk fluid source may be a holding tank
or other storage reservoir having a volume from about 1000 gallons
to about 20 million gallons or more, preferably from about 1000
gallons to about 12 million gallons. In such an embodiment, the
treated peracid use solutions provide a peracid concentration (e.g.
peracetic acid) in the bulk water source from 0.1 ppm to about 100
ppm peracid or greater, preferably from about 1 ppm to about 100
ppm peracid or greater. Without being limited according to the
mechanism and/or the scope of the invention, all ranges are
included within the scope of the invention.
[0206] According to the various aspects of the invention,
monitoring devices and/or means may be included to measure the
application rate and/or bulk solution of peracid in order to ensure
either the application rate of peracid (or the bulk solution having
a maintained peracid) at a concentration of from 0.1 ppm to about
100 ppm peracid or greater, preferably from about 1 ppm to about
100 ppm peracid or greater.
[0207] In an aspect, the treated peracid use solutions may be added
to dormant water sources. As one skilled in the art will ascertain,
the use of treated peracid use solutions in dormant water sources
will often require less frequent dosing that other water sources.
For example, use of the treated water sources during non-pumping
(e.g. non-use) periods, such as for example winter, will require
less frequent dosing due to the more static nature of the water
source at that particular time.
[0208] In a still further aspect, the treated peracid use solutions
are added to waters in need of treatment before disposal. In such
an aspect, flow back waters (e.g. post fracking) are treated to
minimize microbial contaminations in the waters and to remove
solids prior to disposal of the water into a subterranean well,
reuse in a subsequent fracturing application or return of the water
into local environmental water sources. Such flow back waters may
be held, for example, in tanks, ponds or the like, in some aspects
of the invention.
[0209] In an aspect, the water source in need of treatment may vary
significantly. For example, the water source may be a freshwater
source (e.g. pond water), salt water or brine source, brackish
water source, recycled water source, or the like. In an aspect,
wherein offshore well drilling operations are involved, seawater
sources are often employed (e.g. saltwater or non-saltwater).
Beneficially, the peracid and peroxide-reducing agent compositions
of the invention are suitable for use with any types of water and
provide effective antimicrobial efficiency with any of such water
sources.
[0210] Large volumes of water are employed according to the
invention as required in well fluid operations. As a result, in an
aspect of the invention, recycled water sources (e.g. produced
waters) are often employed to reduce the amount of a freshwater,
pond water or seawater source required. Recycled or produced water
are understood to include non-potable water sources. The use of
such produced waters (in combination with freshwater, pond water or
seawater) reduces certain economic and/or environmental
constraints. In an aspect of the invention, thousands to millions
of gallons of water may be employed and the combination of produced
water with fresh water sources provides significant economic and
environmental advantages.
[0211] In an aspect of the invention, as much produced water as
practical is employed. In an embodiment at least 1% produced water
is employed, preferably at least 5% produced water is employed,
preferably at least 10% produced water is employed, preferably at
least 20% produced water is employed, or more preferably more than
20% produced water is employed. Without being limited according to
the mechanism and/or the scope of the invention, all ranges are
included within the scope of the invention.
[0212] The treated water source can comprise any suitable
concentration of the C.sub.1-C.sub.22 percarboxylic acid. In some
embodiments, the treated water source comprises from about 10 ppm
to about 200 ppm of the C.sub.1-C.sub.22 percarboxylic acid. In
other embodiments, the treated water source comprises about 1 ppm,
10 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700
ppm, 800 ppm, 900 ppm or 1,000 ppm of the C.sub.1-C.sub.22
percarboxylic acid. The present methods can be used to treat any
suitable or desirable water sources. In another example, the
present methods can be used to treat fresh water, pond water, sea
water, produced water and a combination thereof. In some
embodiments, the water source comprises at least about 1 wt-%
produced water. In other embodiments, the water source comprises at
least about 1 wt-%, 2 wt-%, 3 wt-%, 4 wt-%, 5 wt-%, 6 wt-%, 7 wt-%,
8 wt-%, 9 wt-%, or 10 wt-%, 15 wt-%, 20 wt-%, 25 wt-%, 30 wt-% or
more produced water.
[0213] In an aspect of the invention, the method includes a
pretreatment step, wherein the peracid composition is treated with
a peroxide-reducing agent to reduce the hydrogen peroxide
concentration in a use solution. The pretreatment step occurs prior
to combining the peracid antimicrobial composition and/or
peroxide-reducing agent to a water source in need of treatment. In
an aspect of the invention, the pretreatment may occur within a few
minutes to hours before addition to a water source. Preferably, a
commercial peracid formulation is employed (e.g. peracetic acid).
Thereafter, the peracid and peroxide-reducing agent composition use
solution may be diluted to obtain the desired peracetic acid
concentrations, with low and/or no hydrogen peroxide
concentration.
[0214] According to embodiments of the invention, a sufficient
amount of the pretreated peracid and peroxide-reducing agent use
solution composition is added to the aqueous water source in need
of treatment to provide the desired peracid concentration for
antimicrobial efficacy. For example, a water source is dosed
amounts of the peracid and peroxide-reducing agent use solution
composition until a peracid concentration within the water source
is detected within the preferred concentration range (e.g. about 1
ppm to about 100 ppm peracid). In an aspect, it is preferred to
have a microbial count of less than about 100,000 microbes/mL, more
preferably less than about 10,000 microbes/mL, or more preferably
less than about 1,000 microbes/mL. Without being limited according
to the mechanism and/or the scope of the invention, all ranges are
included within the scope of the invention.
[0215] In some embodiments, the level of a microorganism, if
present in the water source, is stabilized or reduced by the
present methods. For example, at least 10%, 20%, 30%, 40%, 50%,
60%, 70%, 80%, or 90% or more of the microorganism, if present in
the water source, is killed, destroyed, removed and/or inactivated
by the present methods. In a further aspect of the invention, the
method includes a pretreatment step of the water source. In some
aspects, the water source in need of treatment may be first dosed
an acidulant to decrease the pH of the water source. Beneficially,
in an aspect of the invention, the pretreatment of a water source
with an acidulant provides increased peracid stability within the
water source.
[0216] The methods of use as described herein can vary in the
temperature and pH conditions associated with use of the aqueous
treatment fluids. For example, the aqueous treatment fluids may be
subjected to varying ambient temperatures according to the
applications of use disclosed herein, including ranging from about
0.degree. C. to about 180.degree. C. in the course of the treatment
operations. Preferably, the temperature range is between about
5.degree. C. to about 100.degree. C., more preferably between about
10.degree. C. to about 80.degree. C. Without being limited
according to the mechanism and/or the scope of the invention, all
ranges are included within the scope of the invention. However, as
a majority of the antimicrobial activity of the compositions of the
invention occurs over a short period of time, the exposure of the
compositions to relatively high temperatures is not a substantial
concern.
[0217] In addition, the peracid composition aqueous treatment
fluids (i.e. use solutions) may be subjected to varying pH ranges,
such as from 1 to about 10.5. Preferably, the pH range is less than
about 9, less than about 8.2 (pKa value of the representative
peracid peracetic acid) to ensure the effective antimicrobial
efficacy of the peracid. In some aspects of the invention, a pH
modifier (such as an acidulant) is added to a water source in need
of treatment according to the invention. In some embodiments it may
be desirable to decrease the pH to between about 5 and about 8.5.
Without being limited according to the mechanism and/or the scope
of the invention, all ranges are included within the scope of the
invention.
[0218] The antimicrobial compositions of the invention are
fast-acting. However, the present methods require a certain minimal
contact time of the compositions with the water in need of
treatment for occurrence of sufficient antimicrobial effect. The
contact time can vary with concentration of the use compositions,
method of applying the use compositions, temperature of the use
compositions, pH of the use compositions, amount of water to be
treated, amount of soil or substrates in the water to be treated,
or the like. The contact or exposure time can be at least about 15
seconds. In some embodiments, the exposure time is about 1 to 5
minutes. In other embodiments, the exposure time is at least about
10 minutes, 30 minutes, or 60 minutes. In other embodiments, the
exposure time is a few minutes to hours. In other embodiments, the
exposure time is a few days or more. Beneficially, the compositions
for use according to the invention are suitable for short contact
times due in part to the non-oxidizing nature of the compositions
having reduced or eliminated hydrogen peroxide content. The contact
time will further vary based upon the concentration of peracid in a
use solution.
[0219] In further aspects of the invention, the methods include the
direction of the treated water compositions into a subterranean
environment and/or a well-bore. In some aspects, the treated water
compositions are directed into a subterranean environment and/or a
well-bore at a speed faster than about 30 barrel (bbl.)/minute,
faster than about 60 barrel (bbl.)/minute, and/or at a speed of
about 65 barrel (bbl.)/minute and about 100 barrel (bbl.)/minute.
Without being limited according to the mechanism and/or the scope
of the invention, all ranges are included within the scope of the
invention. As referred to herein, a subterranean environment may
include, for example, a shale gas reservoir, a well, and/or an oil
reservoir.
[0220] Beneficial Affects of the Methods of Use in Water
Treatment
[0221] In some aspects, the methods disclosed for water treatment
in oil and gas recovery provide effective antimicrobial efficacy
without deleterious interaction with functional agents, including
for example friction reducers. In a further aspect, the methods for
water treatment provide increased antimicrobial efficacy compared
to the use of the antimicrobial peracids alone. In a still further
aspect, the methods of use result in the disposal of cleaner water
with low numbers of microorganisms. In yet a further aspect of the
methods of the invention, the reduction and/or elimination of
H.sub.2O.sub.2 from the peracid compositions minimizes the negative
effects of the oxidant H.sub.2O.sub.2.
[0222] In an aspect, the methods of use provide an antimicrobial
for use that does not negatively impact the environment.
Beneficially, the degradation of the compositions of the invention
provides a "green" alternative. In an aspect of the invention,
utilizing peroxyacetic acid is beneficial as the by-products are
non-toxic, non-persistent in the environment, certified as organic
and permitted for discharge in surface waters.
[0223] In a further aspect, the methods of use provide an
antimicrobial for use that does not negatively interfere with
friction reducers, viscosity enhancers and/or other functional
ingredients. In a further aspect, the methods of use do not
negatively interfere with any additional functional agents utilized
in the water treatment methods, including for example, corrosion
inhibitors, descaling agents, UV blocking agents, and the like. The
compositions administered according to the invention provide
extremely effective control of microorganisms without adversely
affecting the functional properties of any additive polymers of an
aqueous system. In addition, the treated peracid composition use
solutions provide additional benefits to a system, including for
example, reducing corrosion within the system due to the decreased
or substantially eliminated hydrogen peroxide from a treated
peracid composition. Beneficially, the non-deleterious effects of
the treated peracid compositions (namely using a peroxide-reducing
agent) on the various functional ingredients used in water
treatment methods are achieved regardless of the make-up of the
water source in need of treatment.
[0224] In an additional aspect, the methods of use prevent the
contamination of systems, such as well or reservoir souring. In
further aspects, the methods of use prevent
microbiologically-influenced corrosion of the systems upon which it
is employed.
[0225] In additional aspects of the invention, the reduction and/or
elimination of hydrogen peroxide from the systems reduces volume
expansion within sealed systems (e.g. wells). As a result there is
a significantly decreased or eliminated risk of well blow outs due
to the removal of gases within the antimicrobial compositions used
for treating the various water sources.
[0226] In further aspects, the methods of use employ the
antimicrobial and/or bleaching activity of the peracid
compositions. For example, the invention includes a method for
reducing a microbial population and/or a method for bleaching.
These methods can operate on an article, surface, in a body or
stream of water or a gas, or the like, by contacting the article,
surface, body, or stream with the compositions. Contacting can
include any of numerous methods for applying the compositions,
including, but not limited to, providing the antimicrobial peracid
compositions in an aqueous use solution and immersing any articles,
and/or providing to a water source in need of treatment.
[0227] The compositions are suitable for antimicrobial efficacy
against a broad spectrum of microorganisms, providing broad
spectrum bactericidal and fungistatic activity. For example, the
peracid biocides of this invention provide broad spectrum activity
against wide range of different types of microorganisms (including
both aerobic and anaerobic microorganisms), including bacteria,
yeasts, molds, fungi, algae, and other problematic microorganisms
associated with oil- and gas-field operations.
[0228] Exemplary microorganisms susceptible to the peracid
compositions of the invention include, gram positive bacteria
(e.g., Staphylococcus aureus, Bacillus species (sp.) like Bacillus
subtilis, Clostridia sp.), gram negative bacteria (e.g.,
Escherichia coli, Pseudomonas sp., Klebsiella pneumoniae,
Legionella pneumophila, Enterobacter sp., Serratia sp.,
Desulfovibrio sp., and Desulfotomaculum sp.), yeasts (e.g.,
Saccharomyces cerevisiae and Candida albicans), molds (e.g.,
Aspergillus niger, Cephalosporium acremonium, Penicillium notatum,
and Aureobasidium pullulans), filamentous fungi (e.g., Aspergillus
niger and Cladosporium resinae), algae (e.g., Chlorella vulgaris,
Euglena gracilis, and Selenastrum capricornutum), and other
analogous microorganisms and unicellular organisms (e.g.,
phytoplankton and protozoa).
[0229] Use in Other Treatments
[0230] Additional embodiments of the invention include water
treatments for various industrial processes for treating liquid
systems. As used herein, "liquid system" refers to flood waters or
an environment within at least one artificial artifact, containing
a substantial amount of liquid that is capable of undergoing
biological fouling. Liquid systems include but are not limited to
industrial liquid systems, industrial water systems, liquid process
streams, industrial liquid process streams, industrial process
water systems, process water applications, process waters, utility
waters, water used in manufacturing, water used in industrial
services, aqueous liquid streams, liquid streams containing two or
more liquid phases, and any combination thereof.
[0231] In a further aspect, the compositions and methods can also
be used to treat other liquid systems where both the compositions'
antimicrobial function and oxidant properties can be utilized.
Aside from the microbial issues surrounding waste water, waste
water is often rich in malodorous compounds of reduced sulfur,
nitrogen or phosphorous. A strong oxidant such as the compositions
disclosed herein converts these compounds efficiently to their odor
free derivatives e.g. the sulfates, phosphates and amine oxides.
These same properties are very useful in the pulp and paper
industry where the property of bleaching is also of great
utility.
[0232] In a still further aspect, the compositions and methods can
also be used for various aseptic treatment uses. Description of
various applications of use of treated peracid compositions having
low or reduced hydrogen peroxide are disclosed for example in U.S.
Pat. No. 8,226,939, entitled "Antimicrobial Peracid Compositions
with Selected Catalase Enzymes and Methods of Use in Aseptic
Packaging," which is incorporated by reference in its entirety.
[0233] In an aspect, aseptic packaging fillers, including both
categories: a single use filler and a re-use or recirculating
filler, are suitable for using the compositions and methods of the
invention. The single use system makes a dilute stock solution of
peracid. It sprays a small amount of this solution in the inside of
a package to sterilize it. The solution can be heated at the point
of injection or it can be pre-heated prior to injection into the
bottle. In either case the running conditions (temperature, contact
time, and peracid concentration) are chosen so that the bottle is
rendered commercially sterile. After contacting in the inside of
the bottle, this spent solution drains from the bottle and is
exported by the filler either to a drain or to other parts of the
machine for environmental antimicrobial treatments or treatment of
the exterior of the bottles. After the bottle has been treated it
will be rinsed with microbial pure water, filled with a liquid food
and sealed. All of these steps occur inside of a positive pressure
zone inside the filler called the sterile zone. In a re-use filler,
the filler contains a sump of diluted peracid solution. This sump
is held at the desired temperature (40-65.degree. C.). The filler
draws from this sump and uses the solution to sterilize both the
inside and outside of the bottles. The solution drains away from
the bottles and it is collected and exported back to the same sump
from which it originated. After the bottle has been treated it will
be rinsed with microbiologically pure water, filled with a liquid
food and sealed. All of these steps occur inside of a positive
pressure zone inside the filler called a sterile zone.
[0234] In a further aspect, the compositions and methods can be
used in aseptic packaging, including contacting the container with
a composition according to the present invention. Such contacting
can be accomplished using a spray device or soaking tank or vessel
to intimately contact the inside of the container with the
composition for sufficient period of time to clean or reduce the
microbial population in the container. The container is then
emptied of the amount of the present composition used. After
emptying, the container can then be rinsed with potable water or
sterilized water (which can include a rinse additive) and again
emptied. After rinsing, the container can be filled with the food.
The container is then sealed, capped or closed and then packed for
shipment for ultimate sale. Examples of containers that can be
filled include polyethylene terephthalate (PET), high density
polyethylene (HDPE), polypropylene (PP), low density polyethylene,
polycarbonate (PC), poly vinyl alcohol (PVA), aluminum, single or
multilayer films or pouches, paperboard, steel, glass, multilayer
bottles, other polymeric packaging material, combinations of these
materials in films, pouches, bottle, or other food packaging
materials.
[0235] Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, numerous
equivalents to the specific procedures, embodiments, claims, and
examples described herein. Such equivalents are considered to be
within the scope of this invention and covered by the claims
appended hereto. The contents of all references, patents, and
patent applications cited throughout this application are hereby
incorporated by reference to the same extent as if each individual
publication or patent application was specifically and individually
indicated as incorporated by reference. All publications and patent
applications in this specification are indicative of the level of
ordinary skill in the art to which this invention pertains. The
invention is further illustrated by the following examples, which
should not be construed as further limiting.
EXAMPLES
[0236] Embodiments of the present invention are further defined in
the following non-limiting Examples. It should be understood that
these Examples, while indicating certain embodiments of the
invention, are given by way of illustration only. From the above
discussion and these Examples, one skilled in the art can ascertain
the essential characteristics of this invention, and without
departing from the spirit and scope thereof, can make various
changes and modifications of the embodiments of the invention to
adapt it to various usages and conditions. Thus, various
modifications of the embodiments of the invention, in addition to
those shown and described herein, will be apparent to those skilled
in the art from the foregoing description. Such modifications are
also intended to fall within the scope of the appended claims.
Example 1
[0237] Corrosion test were conducted. Corrosion rates were
determined by a wheel box test, using bottles on a wheel in an
oven. Each bottle contained a 1018 carbon steel coupon used for
weight loss analysis upon completion of the test. The test was
conducted using produced water (e.g. recycled water) from an
oil/gas well and deionized water. The test was run at room
temperature and in triplicates. The average corrosion rates were
compared to blank samples (no chemical added). PAA/H.sub.2O.sub.2
was dosed at 50, 300 and 900 ppm. Catalase was added at 1000 ppm.
The test duration was 24 hours.
[0238] Results. The results from the corrosion tests for produced
and deionized water are shown in FIG. 1. For a produced water
sample, addition of 1000 ppm catalase to the PAA/H.sub.2O.sub.2
treatment decreased the corrosion rates of the 1018 carbon steel by
approximately 30-50% (FIG. 1). In deionized water the reduction in
corrosion rates reached almost 60% (FIG. 2).
Example 2
[0239] An evaluation of friction reducer interference was
conducted. Viscosity measurements were obtained using a FANN Model
35 Viscometer. A total of 600 ml of tap water containing a friction
reducer was treated with 200 ppm and 1000 ppm of peracetic acid
with and without catalase. The mixture was blended for 15 seconds
with a Hamilton Beach hand mixer and viscosity was measured at 300
rpm, room temperature. Viscosity values are reported in centipoise
(cP).
[0240] Results. Table 1 shows the impact of PAA/H.sub.2O.sub.2 on
friction reducers within a water source for oil/gas recovery, with
and without the addition of catalase. A negative effect of the
PAA/H.sub.2O.sub.2 was observed on both friction reducers. However,
the effect was reduced in all cases following treatment with
catalase indicating the addition of catalase to remove
H.sub.2O.sub.2 reduces any negative impact of PAA/H.sub.2O.sub.2 on
the friction reducers.
TABLE-US-00001 TABLE 1 With (Yes)/ Friction Without Reading Reading
Biocide Reducer (NO) before after dosage (1 gpt) catalase chemical
chemical Difference PAA/H.sub.2O.sub.2 200 ppm FR#1 No 5.5 4.5 -1
PAA/H.sub.2O.sub.2 200 ppm FR#1 Yes 5 4.25 -0.75 PAA/H.sub.2O.sub.2
200 ppm FR#2 No 3 2.5 -0.5 PAA/H.sub.2O.sub.2 200 ppm FR#2 Yes 2.75
2.5 -0.25 PAA/H.sub.2O.sub.2 1000 ppm FR#1 No 5.5 2.75 -2.75
PAA/H.sub.2O.sub.2 1000 ppm FR#1 Yes 5 2.75 -2.75
PAA/H.sub.2O.sub.2 1000 ppm FR#2 No 3 2.25 -0.75 PAA/H.sub.2O.sub.2
1000 ppm FR#2 Yes 2.75 2.75 0
Example 3
[0241] The impact of water pretreatment with 500 ppm of the
EnviroSan product (75 ppm POAA) on micro efficacy in various
fracking water mixtures were evaluated. The example represents a
baseline data set of various water treatment options according to
the invention. Table 2 and FIG. 3 show the average log reduction in
various slick water treatments with varying ppm PAA (without any
catalase treatment or pretreatment), representing a baseline data
set.
TABLE-US-00002 TABLE 2 Holding Percentage Tank Pre- Reuse Slick
Avg. Log.sub.10 Reduction treatment H.sub.2O Water Treatment 2.5
minutes 5 minutes None 0% 22 ppm NO 5.53 5.75 POAA Catalase 75 ppm
PAA 10% 29 ppm NO 6.45 6.71 POAA Catalase None 36 ppm 4.32 4.72
POAA 75 ppm PAA 20% 47 ppm NO 6.42 6.55 PAA Catalase None 86 ppm
4.57 4.64 POAA 75 ppm PAA 30% 86 ppm NO 6.47 6.41 POAA Catalase
None 138 ppm 4.12 5.00 POAA
FIG. 3 shows the increasing amount of POAA required in tested water
samples having increased amounts of produced water (e.g. reused
water).
Example 4
[0242] Planktonic kill studies were performed as an evaluation of
biocide efficiency for PAA/H.sub.2O.sub.2 and
PAA/H.sub.2O.sub.2/Catalase applications. Briefly, produced water
samples were used to test the kill efficiency of PAA/H.sub.2O.sub.2
at the following dosages: 25, 50, 75, 150 and 300 ppm PAA.
Concentration of catalase was fixed at 1000 ppm. The contact time
was set to 10 and 60 minutes. After contact time, bacterial
enumeration was performed using ATP quantification assay. Bacterial
enumeration was calculated at the end of the appropriate time and
biocide efficacy determined by comparison to an untreated
sample.
[0243] Results. Planktonic kill studies demonstrate the addition of
catalase increased microbial kill efficiency (FIGS. 4 and 5). For
low dosage application of PAA/H.sub.2O.sub.2 (25 ppm), the addition
of 1000 ppm of catalase increased the biocide efficiency by 48%
after 10 minutes of treatment (23% after 60 minutes). The data from
FIGS. 4 and 5 are also shown in Tables 3A and 3B
(respectively).
TABLE-US-00003 TABLE 3A (10 minute contact) % Reduction compared to
% Reduction compared to Dosage (ppm) blank (PAA/H2O2) blank
(PAA/H2O2/catalase) 25 32.7 80.8 75 71.2 82.1 100 80.5 85.5 300 82
88.1 750 85.3 97.6
TABLE-US-00004 TABLE 3B (60 minute contact) % Reduction compared to
% Reduction compared to Dosage (ppm) blank (PAA/H2O2) blank
(PAA/H2O2/catalase) 25 66.6 89.6 75 90.8 92.8 100 91.6 94 300 92.4
98.4 750 93.4 99.3
Example 5
[0244] Additional biocide testing was completed to assess the use
of peracid and catalase compositions for water treatments used in
oil fracking. The use of the commercially-available approximately
15 wt-% peracid (POAA) composition EnviroSan (Ecolab, Inc., St.
Paul, Minn.) with and without catalase was evaluated for biocide
efficacy in water treatments for oil fracking. In particular, an
EnviroSan stock solution (approximately 1400 ppm POAA) with and
without catalase was evaluated.
[0245] EnviroSan stock solutions with catalase were prepared as
follows: 1 gram of EnviroSan (POAA) was added to 99 gram of
deionized water in a beaker. With stirring, 100 .mu.l of Optimase
CA 400 L (catalase) was added through a syringe, and the stirring
was continued for another 6.5 minutes. The subsequent assay (QATM
317) indicates that the resulting solution contains .about.1400 ppm
peracetic acid, and no detectable H.sub.2O.sub.2. The stock
solution of EnviroSan with catalase is stable for at least 30
minutes without detectable changes on the level of POAA and/or
H.sub.2O.sub.2.
[0246] A test system of Pseudomonas aeruginosa (ATCC 15442) and
natural water bacterial populations was employed. P. aeruginosa
were inoculated at ambient (18-22.degree. C.) temperature using
tryptone glucose extract (TGE) agar plating media and incubated at
35.degree. C. for 48 hours.
[0247] Water mixtures as outlined in Table 3A were provided
(showing the percentage of 100 mL of each water sample type). The
various test substances and the amount of chemistry added to 10 mL
of inoculated water sample to achieve 20 ppm residual POAA after 5
minutes within the water mixture are shown in Table 4B.
TABLE-US-00005 TABLE 4A Water Type A B C* D E* F G* Fresh 100% 90%
90% 80% 80% 70% 70% Produced 10% 10% 20% 20% 30% 30% *Solutions
pretreated with 300 ppm EnviroSan more than 24 hours before micro
evaluation
TABLE-US-00006 TABLE 4B Water Type A B C* D E* F G* Vol. 1% 170
.mu.L 320 .mu.L 320 .mu.L 600 .mu.L 600 .mu.L 960 .mu.L 960 .mu.L
Stock ppm POAA 25 ppm 46 ppm 46 ppm 87 ppm 87 ppm 140 ppm 140
ppm
[0248] Testing methods. Prior (24 hours) to micro testing, water
mixtures C, E and G were mixed and pretreated with 300 ppm
EnviroSan. Water samples were dispensed into sterile 250 mL
Erlenmeyer flasks according to Table 4A, ensuring each flask
contained 100 mL total of test water and mixed water types were
completely homogeneous. Test water mixture was dispensed (24.75 mL)
into a centrifuge tube and 0.25 mL of a 10.sup.8 CFU/mL culture of
P. aeruginosa was added and mixed thoroughly. 1 mL of inoculated
water mixture was serial diluted in PBDW. 10 mL of the inoculated
water mixture was dispensed into 2 individual test tubes, where the
appropriate volume of the EnviroSan solution with or without
catalase (Table 4B) was added to achieve 20 ppm POAA residual to
each test tube in timed intervals and mixed. The methods of Example
5 were employed to make the EnviroSan with catalase stock
solutions. Then neutralized 1 mL samples in 9 mL of 0.5% sodium
thiosulfate were obtained after 2.5 minutes, as well as 5
minutes.
[0249] Results. Aerobic bacterial populations (CFU/mL) present in
water sample mixtures (both not pretreated and pretreated with 300
ppm EnviroSan) after inoculation with a P. aeruginosa culture, as
well as survivors present 2.5 minutes and 5 minutes after the
addition of EnviroSan POAA.+-.catalase were evaluated as shown in
Table 5.
TABLE-US-00007 TABLE 5 Water Av. Sample Test Exposure Log.sub.10
Log.sub.10 Log.sub.10 Type Substance Time CFU/mL Growth Growth
Reduction 100% Fresh After 6.90E+06 6.84 6.84 Inoculation EnviroSan
2.5 minutes 1.00E+01 1.00 1.00 5.84 25 ppm POAA 5 minutes 8.00E+01
1.90 1.90 4.94 15 minutes 6.00E+01 1.78 1.78 5.06 30 minutes
2.00E+01 1.30 1.30 5.54 EnviroSan 2.5 minutes 7.00E+01 1.85 1.85
4.99 25 ppm POAA + 5 minutes 4.00E+01 1.60 1.60 5.24 Catalase 15
minutes 3.00E+01 1.48 1.48 5.36 30 minutes 2.00E+01 1.30 1.30 5.54
90% Fresh/ After 1.05E+07 7.02 7.02 10% Inoculation Produced
EnviroSan 2.5 minutes 1.00E+01 1.00 1.00 6.02 46 ppm POAA 1.00E+01
1.00 5 minutes 3.00E+01 1.48 1.24 5.78 1.00E+01 1.00 After 6.90E+06
6.84 6.84 Inoculation EnviroSan 2.5 minutes 1.00E+01 1.00 1.00 6.02
46 ppm POAA + 1.00E+01 1.00 Catalase 5 minutes 2.00E+01 1.30 1.15
5.87 1.00E+01 1.00 90/10 After 1.03E+07 7.01 7.01 24 hour
Inoculation Pretreatment EnviroSan 2.5 minutes 4.00E+01 1.60 1.45
5.56 by 300 ppm 46 ppm POAA 2.00E+01 1.30 EnviroSan 5 minutes
1.00E+01 1.00 1.00 6.01 Product 1.00E+01 1.00 80% Fresh/ After
1.00E+06 6.00 6.00 20% Inoculation Produced EnviroSan 2.5 minutes
1.00E+01 1.00 1.50 4.50 87 ppm POAA 1.00E+02 2.00 5 minutes
6.00E+01 1.78 1.74 4.26 5.00E+01 1.70 After 1.00E+06 6.00 6.00
Inoculation EnviroSan 2.5 minutes 4.00E+01 1.60 1.30 4.70 87 ppm
POAA + 1.00E+01 1.00 Catalase 5 minutes 4.00E+01 1.60 1.69 4.31
6.00E+01 1.78 80/20 After 1.00E+06 6.00 6.00 24 hour Inoculation
Pretreatment EnviroSan 2.5 minutes 2.00E+01 1.30 1.15 4.85 by 300
ppm 87 ppm POAA 1.00E+01 1.00 EnviroSan 5 minutes 2.00E+01 1.30
1.15 4.85 Product 1.00E+01 1.00 70% Fresh/ After 5.90E+06 6.77 6.77
30% Inoculation Produced EnviroSan 2.5 minutes 5.00E+01 1.70 1.77
5.00 140 ppm 7.00E+01 1.85 POAA 5 minutes 5.00E+01 1.70 1.70 5.07
5.00E+01 1.70 After 6.00E+05 5.78 5.78 Inoculation EnviroSan 2.5
minutes 2.00E+01 1.30 1.50 5.27 140 ppm 5.00E+01 1.70 POAA + 5
minutes 4.00E+01 1.60 1.30 5.47 Catalase 1.00E+01 1.00 70/30 After
1.22E+07 7.09 7.09 24 hour Inoculation Pretreatment EnviroSan 2.5
minutes 1.00E+01 1.00 1.00 6.09 by 300 ppm 140 ppm 1.00E+01 1.00
EnviroSan POAA 5 minutes 1.00E+01 1.00 1.00 6.09 Product 1.00E+01
1.00
[0250] The average log reduction generated after a 2.5 minute
exposure is shown (FIG. 6) at varying concentrations of POAA
required to achieve 20 ppm residual POAA after 5 minutes within its
respective fracking water mixture. Across all tested fracking water
mixtures, there does not appear to be a consistent trend to
indicate that there are significant differences in efficacy
generated between treatment of mixtures with POAA alone vs.
POAA+catalase. The results indicate there is not a significant
difference in bacterial reductions caused by pretreatment of the
water mixtures 24 hours in advance with 300 ppm EnviroSan product,
demonstrating the reduction of hydrogen peroxide with the catalase
does not negatively impact micro efficacy.
[0251] Without being limited to a theory of the invention, it is
likely the dosing of POAA chemistry is sufficiently high to
generate significant kill by itself, without the potential benefits
of water pretreatment or EnviroSan pre-reduction by catalase.
Example 6
[0252] Additional microbial testing was conducted to evaluate
whether fracking waters treated with EnviroSan (POAA) pre-reduced
with catalase (as shown in Example 5 to have significantly reduced
consumption of POAA) result in improved micro efficacy. To evaluate
improvements in micro efficacy, all water mixtures were treated
with the same initial concentration of POAA EnviroSan (30 or 40
ppm) plus catalase, instead of aiming for a residual POAA level and
adjusting initial dosing according to the amount of produced water
present.
[0253] The test systems (P. aeruginosa and natural water) described
in Example 5 were utilized. Water mixtures as outlined in Table 6
were provided (showing the percentage of 100 mL of each water
sample type).
TABLE-US-00008 TABLE 6 Water Type A B C D Fresh 100% 90% 80% 70%
Produced 10% 20% 30%
[0254] Water samples were dispensed into sterile 250 mL Erlenmeyer
flasks according to Table 6, ensuring each flask contained 100 mL
total of test water and mixed water types were completely
homogeneous. 50 mL was saved for titration and 50 mL was used for
micro evaluation. Test water mixture was dispensed (24.75 mL) into
a centrifuge tube and 0.25 mL of a 10.sup.8 CFU/mL culture of P.
aeruginosa was added and mixed thoroughly. 1 mL of inoculated water
mixture was serial diluted in PBDW. 10 mL of the inoculated water
mixture was dispensed into 2 individual test tubes, where the
appropriate volume of the EnviroSan 1 stock solution with catalase
was added to achieve 30 ppm or 40 ppm POAA to each test tube in
timed intervals and mixed. The methods of Example 5 were employed
to make the EnviroSan with catalase stock solutions. Then
neutralized 1 mL samples in 9 mL of 0.5% sodium thiosulfate were
obtained after 2.5 minutes, as well as 5 minutes. Results: Table 7
shows the summary of aerobic bacterial population (CFU/mL) present
in water sample mixtures before and after inoculation with a P.
aeruginosa culture, as well as survivors present 2.5 minutes and 5
minutes after the addition of 30 ppm or 40 ppm POAA+catalase. In
addition, the bottom portion of the table summarizes data for the
treatment of inoculated fresh water with 30 ppm and 40 ppm POAA
alone as a comparison to those pre-reduced with catalase.
TABLE-US-00009 TABLE 7 Water Av. Sample Test Exposure Log.sub.10
Log.sub.10 Log.sub.10 Type Substance Time CFU/mL Growth Growth
Reduction Fresh Before 1.02E+03 3.01 3.01 Pond Inoculation Water
After 1.01E+08 8.00 8.00 Inoculation EnviroSan 2.5 minutes 3.80E+04
4.58 4.31 3.69 30 ppm 1.10E+04 4.04 POAA + 5 minutes 2.04E+03 3.31
2.46 5.55 Catalase 4.00E+01 1.60 EnviroSan 2.5 minutes 1.00E+04
4.00 4.53 3.47 40 ppm 1.15E+05 5.06 POAA + 5 minutes 2.00E+01 1.30
1.15 6.85 Catalase 1.00E+01 1.00 90 Fresh/ Before 1.10E+05 5.04
5.04 10 Inoculation Produced After 9.90E+07 8.00 8.00 Inoculation
EnviroSan 2.5 minutes 6.00E+03 3.78 2.74 5.26 30 ppm 5.00E+01 1.70
POAA + 5 minutes 1.00E+01 1.00 1.70 6.30 Catalase 2.50E+02 2.40
EnviroSan 2.5 minutes 1.37E+03 3.14 2.91 5.08 40 ppm 4.90E+02 2.69
POAA + 5 minutes 6.00E+01 1.78 1.78 6.22 Catalase 6.00E+01 1.78 80
Fresh/ Before 1.80E+05 5.26 5.26 20 Inoculation Produced After
8.50E+07 7.93 7.93 Inoculation EnviroSan 2.5 minutes 4.00E+02 2.60
2.22 5.71 30 ppm 7.00E+01 1.85 POAA + 5 minutes 2.60E+02 2.41 1.71
6.22 Catalase 1.00E+01 1.00 EnviroSan 2.5 minutes 1.00E+01 1.00
1.35 6.58 40 ppm 5.00E+01 1.70 POAA + 5 minutes 6.00E+01 1.78 1.39
6.54 Catalase 1.00E+01 1.00 70 Fresh/ Before 2.30E+05 5.36 5.36 30
Inoculation Produced After 9.50E+07 7.98 7.98 Inoculation EnviroSan
2.5 minutes 1.00E+01 1.00 1.00 6.98 30 ppm 1.00E+01 <1.00 POAA +
5 minutes 1.00E+01 <1.00 <1.00 >6.98 Catalase 1.00E+01
<1.00 EnviroSan 2.5 minutes 1.00E+01 1.00 1.00 6.98 40 ppm
1.00E+01 1.00 POAA + 5 minutes 2.00E+01 1.30 1.39 6.59 Catalase
3.00E+01 1.48 Fresh Before 1.02E+03 3.01 3.01 Pond Inoculation
Water After 1.01E+08 8.00 8.00 Inoculation EnviroSan 2.5 minutes
2.35E+03 3.37 3.85 4.16 30 ppm 2.10E+04 4.32 POAA 5 minutes
8.00E+01 1.90 1.93 6.08 9.00E+01 1.95 EnviroSan 2.5 minutes
2.00E+04 4.30 3.97 4.04 40 ppm 4.32E+03 3.64 POAA 5 minutes
1.20E+02 2.08 1.78 6.23 3.00E+01 1.48
[0255] Titration data showing POAA consumption was also analyzed
and shown in Table 8. The titration data indicates the addition of
catalase to the EnviroSan test substance significantly lowers the
degradation rate of POAA within the water mixture over 5 minutes as
compared to equivalent dosing of chemistry not pre-reduced with
catalase.
TABLE-US-00010 TABLE 8 Actual Titrated Concentration (ppm POAA)
Water Mixture Desired Concentration 1 minute 5 minutes 100% Fresh
30 ppm POAA + 25 ppm 27 ppm Catalase 40 ppm POAA + 35 ppm 36 ppm
Catalase 90% Fresh/10% 30 ppm POAA + 26 ppm 27 ppm Produced
Catalase 40 ppm POAA + 34 ppm 36 ppm Catalase 30 ppm POAA 21 ppm 8
ppm 40 ppm POAA 30 ppm 16 ppm 80% Fresh/20% 30 ppm POAA + 23 ppm 24
ppm Produced Catalase 40 ppm POAA + 31 ppm 33 ppm Catalase 30 ppm
POAA 13 ppm 0 ppm 40 ppm POAA 21 ppm 2 ppm 70% Fresh/30% 30 ppm
POAA + 24 ppm 42 ppm Produced Catalase 40 ppm POAA + 18 ppm 33 ppm
Catalase 30 ppm POAA 7 ppm 0 ppm 40 ppm POAA 12 ppm 0 ppm
[0256] The average log reduction generated after a 2.5 minute
exposure time to 30 ppm or 40 ppm POAA EnviroSan with or without
catalase in different fracking water mixtures is shown in Table 8
and FIG. 7. The addition of catalase to the EnviroSan test
substance appears to have no impact on efficacy generated against
organisms present in the inoculated fresh water samples. The data
also suggests that with increasing amounts of produced water within
the tested water mixture, there is increased efficacy generated
within the 2.5 and 5 minute exposure times when treated with
EnviroSan pre-reduced with catalase.
Example 7
[0257] Additional micro efficacy performance was evaluated to
confirm the improved micro efficacy observed in Example 6 when
using increasing amounts of produced water with the dosing static
initial concentrations of POAA (30 ppm or 40 ppm) with catalase.
Improved micro efficacy with increased amounts of produced water
present in a mixture is a highly counterintuitive result and was
unexpected. Under normal conditions, it would be expected to have
decreased micro efficacy as the amount of produced water (e.g.
recycled) increases and the amount of POAA remains static as a
result of the increased contamination found in produced water as
opposed to fresh water sources. As a result, subsequent evaluation
observed the activity of the water itself against a spiked culture
of P. aeruginosa over a 1 hour exposure period to determine whether
the produced water itself has an antimicrobial present.
[0258] All water mixtures were treated with an initial
concentration of 30 ppm POAA EnviroSan, both with and without the
addition of catalase. The data set evaluates whether there is a
significant difference in micro activity generated between
treatments of EnviroSan alone vs. EnviroSan pre-reduced with
catalase.
[0259] All ratios of fracking water mixtures tested (100/0, 90/10,
80/20 & 70/30) were freshly mixed solutions, as well as
solutions mixed and pretreated with 500 ppm EnviroSan product more
than 1 hour before the start of the micro evaluation, in order to
observe if a pretreatment step is of value for micro performance
compared to those mixtures not pretreated. The test system (P.
aeruginosa and natural water) described in Example 5 was again
utilized. Water mixtures as outlined in Table 9 were provided
(showing the percentage of 100 mL of each water sample type).
TABLE-US-00011 TABLE 9 Water Type A B C* D E* F G* Fresh 100% 90%
90% 80% 80% 70% 70% Produced 10% 10% 20% 20% 30% 30% *Solutions
pretreated with 500 ppm EnviroSan more than1 hour before micro
evaluation.
[0260] The testing methods of Example 5 were utilized for the
chemically treated water samples, differing only in the combination
of the 10 mL inoculated water mixtures with appropriate volumes of
the EnviroSan with or without catalase to achieve 30 ppm POAA
residual to each test tube in timed intervals and mixed. The
methods of Example 5 were employed to make the EnviroSan with
catalase stock solutions. In comparison, for the water samples that
were not chemically treated, 9.9 mL of test water mixture was
dispensed into 2 individual test tubes. 0.10 mL of an approximate
10.sup.8 CFU/mL culture of P. aeruginosa was added in timed
intervals and mixed thoroughly. Then 1 mL samples were neutralized
in 9 mL of 0.5% sodium thiosulfate, followed by serial dilution and
enumeration after 2.5 minutes, 5 minutes and 60 minute exposure
times.
[0261] Table 10 shows a summary of aerobic bacterial population
(CFU/mL) present in the water sample mixtures (both not pretreated
and pretreated with 500 ppm EnviroSan) before and after inoculation
with a P. aeruginosa culture, as well as survivors present 2.5
minutes and 5 minutes after the addition of 30 ppm POAA with or
without catalase. In addition, data for enumeration of water
samples for antimicrobial activity against P. aeruginosa over 60
minutes exposure are also summarized in Table 10.
TABLE-US-00012 TABLE 10 Water Av. Sample Exposure Log.sub.10
Log.sub.10 Log.sub.10 Type Test Substance Time CFU/mL Growth Growth
Reduction Pseudomonas aeruginosa ATCC 15442 Fresh Before 3.10E+04
4.49 4.49 Pond Inoculation Water After 7.30E+07 7.86 7.92
Inoculation 9.50E+07 7.98 EnviroSan 2.5 minutes 1.99E+03 3.30 3.30
4.62 30 ppm POAA + 5 minutes 5.00E+01 1.70 1.70 6.22 Catalase
EnviroSan 2.5 minutes 1.90E+03 3.28 3.28 4.64 30 ppm POAA 5 minutes
4.40E+01 1.64 1.64 6.28 No Chemical 2.5 minutes 5.24E+07 7.72 7.72
0.20 Treatment 5 minutes 4.28E+07 7.63 7.63 0.29 60 minutes
5.64E+07 7.75 7.75 0.17 90 Fresh/ Before 1.22E+04 4.09 4.09 10
Inoculation Produced After 7.10E+07 7.85 7.80 Inoculation 5.70E+07
7.76 EnviroSan 2.5 minutes 3.30E+02 2.52 2.52 5.29 30 ppm POAA + 5
minutes 7.00E+01 1.85 1.85 5.96 Catalase EnviroSan 2.5 minutes
5.30E+04 4.72 4.72 3.08 30 ppm POAA 5 minutes 8.00E+03 3.90 3.90
3.90 No Chemical 2.5 minutes 5.56E+07 7.75 7.75 0.06 Treatment 5
minutes 5.04E+07 7.70 7.70 0.10 60 minutes 5.24E+07 7.72 7.72 0.08
90 Fresh/ Before 1.20E+01 1.08 1.08 10 Inoculation Produced After
6.70E+07 7.83 7.85 Pretreated Inoculation 7.60E+07 7.88 with
EnviroSan 2.5 minutes 6.00E+01 1.78 1.78 6.08 500 ppm 30 ppm POAA +
5 minutes 5.00E+01 1.70 1.70 6.15 EnviroSan Catalase EnviroSan 2.5
minutes 6.00E+01 1.78 1.78 6.08 30 ppm POAA 5 minutes 3.00E+01 1.48
1.48 6.38 80 Fresh/ Before 1.39E+04 4.14 4.14 20 Inoculation
Produced After 6.50E+07 7.81 7.84 Inoculation 7.20E+07 7.86
EnviroSan 2.5 minutes 1.30E+02 2.11 2.11 5.72 30 ppm POAA + 5
minutes 3.00E+01 1.48 1.48 6.36 Catalase EnviroSan 2.5 minutes
4.48E+05 5.65 5.65 2.18 30 ppm POAA 5 minutes 2.86E+05 5.46 5.46
2.38 No Chemical 2.5 minutes 5.00E+07 7.70 7.70 0.14 Treatment 5
minutes 5.32E+07 7.73 7.73 0.11 60 minutes 4.64E+07 7.67 7.67 0.17
80 Fresh/ Before 2.50E+01 1.40 1.40 20 Inoculation Produced After
5.70E+07 7.76 7.82 Pretreated Inoculation 7.70E+07 7.89 with
EnviroSan 2.5 minutes 5.00E+01 1.70 1.70 6.12 500 ppm 30 ppm POAA +
5 minutes 4.00E+01 1.60 1.60 6.22 EnviroSan Catalase EnviroSan 2.5
minutes 1.50E+03 3.18 3.18 4.65 30 ppm POAA 5 minutes 6.00E+01 1.78
1.78 6.04 70 Fresh/ Before 1.61E+04 4.21 4.21 30 Inoculation
Produced After 6.70E+07 7.83 7.83 Inoculation 6.90E+07 7.84
EnviroSan 2.5 minutes 3.40E+02 2.53 2.53 5.30 30 ppm POAA + 5
minutes 7.00E+01 1.85 1.85 5.99 Catalase EnviroSan 2.5 minutes
9.00E+05 5.95 5.95 1.88 30 ppm POAA 5 minutes 8.00E+05 5.90 5.90
1.93 No Chemical 2.5 minutes 5.48E+07 7.74 7.74 0.09 Treatment 5
minutes 4.56E+07 7.66 7.66 0.17 60 minutes 4.72E+07 7.67 7.67 0.16
70 Fresh/ Before 4.10E+01 1.61 1.61 30 Inoculation Produced After
6.40E+07 7.81 7.82 Pretreated Inoculation 6.90E+07 7.84 with
EnviroSan 2.5 minutes 9.60E+02 2.98 2.98 4.84 500 ppm 30 ppm POAA +
5 minutes 7.50E+02 2.88 2.88 4.95 EnviroSan Catalase EnviroSan 2.5
minutes 1.30E+04 4.11 4.11 3.71 30 ppm POAA 5 minutes 5.64E+03 3.75
3.75 4.07 Sterile DI No Chemical 2.5 minutes 5.52E+07 7.74 7.74
Water Treatment 5 minutes 5.84E+07 7.77 7.77 60 minutes 5.16E+07
7.71 7.71
[0262] The water sample mixtures according to this study are
summarized in Tables 11A-B, showing the water sample mixtures and
chemical treatments (Table 10A) and the titrated concentrations of
POAA (Table 11B).
TABLE-US-00013 TABLE 11A Water Sample Mixture Treatment C1 80/20
Pretreated with 500 ppm 30 ppm POAA EnviroSan EnviroSan .gtoreq.1
hour before study C2 80/20 30 ppm POAA EnviroSan + Catalase C3
80/20 30 ppm POAA EnviroSan C4 80/20 No Chemical Treatment
TABLE-US-00014 TABLE 11B Titrated Concentration (ppm POAA) Test
Solution 0 minutes 1 minute 5 minutes C1 30 ppm 22 ppm 9 ppm C2 30
ppm 26 ppm 24 ppm C3 30 ppm 14 ppm 0 ppm C4 0 ppm 0 ppm 0 ppm
[0263] The titration data confirms that the addition of catalase to
the EnviroSan test substance significantly lowers the degradation
rate of POAA within the water mixture over 5 minutes as compared to
equivalent dosing of chemistry not pre-reduced with catalase. In
addition, water pretreated with H.sub.2O.sub.2 1 hour prior to
testing slightly reduces POAA degradation, as well, however not
nearly as significantly as using pre-reduced EnviroSan by catalase
as the test substance.
[0264] Table 11C show the use of 30 ppm POAA with/without catalase
treatment compared for micro performance at both 2.5 and 5.0
minutes exposure times. Upon addition of 10-30% reuse water a
defined drop in antimicrobial performance was observed over both
2.5 and 5 minutes as peracid was rapidly consumed if not pretreated
with catalase. A residual of 30 ppm POAA at 5 minutes was needed to
achieve the desired antimicrobial performance.
TABLE-US-00015 TABLE 11C Holding Tank Percentage Avg. Log.sub.10
Reduction Pretreatment Reuse H.sub.2O Slick Water Treatment 2.5
minutes 5 minutes None 0% 30 ppm Catalase 4.62 6.22 PAA NO 4.64
6.32 Catalase None 10% 30 ppm Catalase 5.29 5.96 PAA NO 3.09 3.91
Catalase None 20% 30 ppm Catalase 5.73 6.36 PAA NO 2.19 2.38
Catalase None 30% 30 ppm Catalase 5.30 5.98 PAA NO 1.88 1.93
Catalase
[0265] Data showed that in the absence of reuse water (contaminated
water) at 30 ppm POAA with/without catalase treatment both achieved
desired antimicrobial performance. FIGS. 9 and 10 confirm the
findings of no difference in micro efficacy between fresh water
samples treated with 30 ppm POAA alone vs. 30 ppm POAA+catalase at
2.5 minutes (FIG. 9) and 5 minutes (FIG. 10). It is thought that
the use of fresh water does not interfere with the stability of the
POAA and therefore the micro efficacy of the POAA in solution of
fresh waters.
[0266] The data confirm there is a significant difference in
activity generated by POAA vs. POAA+catalase in tested water
mixtures containing produced water. On average, there was at least
a 2 log greater reduction observed for samples treated with
POAA+catalase, than samples treated with POAA alone at the same
time point (FIG. 11). This confirms the enhanced POAA stability and
concomitant micro efficacy in reuse waters with reduced hydrogen
peroxide.
[0267] However, with the pretreatment of water mixtures by 500 ppm
EnviroSan more than 1 hour prior to testing, the differences in
efficacy observed between POAA alone vs. POAA+catalase treatments
were eliminated (FIG. 12). The log survivors present 2.5, 5 and 60
minutes after the addition of a P. aeruginosa culture into
different mixtures of fracking water were nearly equivalent with
the pretreatment of at least an hour before testing, thus
confirming the water alone does not have any antimicrobial
properties.
Example 8
[0268] A micro efficacy comparison of POAA added at levels to
target 30 ppm POAA residuals at 5 minutes versus POAA pretreated
with catalase was conducted as set forth in Table 12.
TABLE-US-00016 TABLE 12 Holding Tank Percentage Avg. Log.sub.10
Reduction Treatment Reuse H.sub.2O Slick Water Treatment 2.5
minutes 5 minutes None 10% 30 ppm Catalase 5.29 5.96 PAA 46 ppm NO
4.32 4.72 PAA Catalase None 20% 30 ppm Catalase 5.73 6.36 PAA 86
ppm NO 4.57 4.64 PAA Catalase None 30% 30 ppm Catalase 5.30 5.98
PAA 138 ppm NO 4.12 5.00 PAA Catalase
[0269] This data further confirms there is an improvement in the
micro efficacy of POAA treated with catalase as opposed to POAA
alone in all tested water mixtures containing at least 10% produced
water. (FIG. 13). This confirms the enhanced POAA stability and
concomitant micro efficacy in reuse waters with reduced hydrogen
peroxide.
Example 9
[0270] The impact of peracid to hydrogen peroxide ratio on the
stability of the peracid in produced waters was evaluated. Various
commercially available peracid use solutions were employed having
the peracid to hydrogen peroxide ratios set forth in Table 13. FIG.
14 shows the increased ratio of peracid to hydrogen peroxide
improves peracid stability.
TABLE-US-00017 TABLE 13 Sample Time (1) POAA/H.sub.2O.sub.2 (2)
POAA/H.sub.2O.sub.2 (3) POAA/H.sub.2O.sub.2 (min.) 8.26 1.37 0.21 0
87 82 89 1 58 56 40 4 48 31 12 5 47 23 3 6 46 14 0
Example 10
[0271] The effect of catalase on the peracid stability within
treated waters was further evaluated. Water blends of 80/20 (80%
fresh water/20% produced water) were employed to analyze the impact
on various treatment sequences set forth in Table 14.
TABLE-US-00018 TABLE 14 Req'd. Enviro Catalase San RM Theoretical
POAA POAA POAA POAA (14.5% Conc Initial Meas'd. Meas'd. Meas'd.
Meas'd. POAA, Treatment Water (ppm): POAA at 1 min. at 4 min. at 5
min. at 6 min. ppm Sequence Blends CA 400 (ppm) (ppm) (ppm) (ppm)
(ppm) w/w) Simult. 80/20 100 82 66 61 65 58 566 Add NA 80/20 0 82
56 31 23 17 566 Simult. 80/20 10 82 63 34 31 26 566 Add Pretreated
80/20 10 82 76 75 75 75 566
[0272] As shown in FIG. 15, the most stable peracid systems were
pretreated with catalase prior to addition to the blended water
sources. Use of 10.times. the catalase yielded inferior results in
comparison to the pretreatment with catalase demonstrating a clear
benefit to pretreatment according to the invention when using
blended compositions. The composition not containing catalase
demonstrated rapid POAA degradation.
[0273] Due to the efficacious results shown in FIG. 15, the same
methods were used to further evaluate a pretreatment using a lower
concentration of the catalase as shown in Table 15.
TABLE-US-00019 TABLE 15 Catalase Theoretical POAA POAA POAA POAA RM
Conc Initial Meas'd. at Meas'd. Meas'd. Meas'd. Treatment Water
(ppm): POAA 1 min. at 4 min. at 5 min. at 6 min. Sequence Blends CA
400 (ppm) (ppm) (ppm) (ppm) (ppm) Simult. 80/20 100 82 66 61 65 58
Add NA 80/20 0 82 56 31 23 17 Simult. 80/20 10 82 63 34 31 26 Add
Pretreated 80/20 5.8 82 76 75 75 75
[0274] As shown in FIG. 16, the decreased catalase used in the
pretreated peracid composition again outperformed the simultaneous
addition of catalase to a peracid system and/or no catalase
system.
Example 11
[0275] The micro efficacy of a 30 ppm POAA (EnviroSan) composition,
a 30 ppm POAA (EnviroSan) with catalase composition and a 30 ppm
mixed peracetic acid and peroctanoic acid peracid composition
(POAA/POOA) were compared (FIG. 17). The micro efficacy was
evaluated using 80% fresh water/20% produced water system from and
oil- and gas-field operation.
[0276] The mixed POAA/POOA composition demonstrated improvements
over use of the 30 ppm POAA composition alone. The same ppm peracid
provided significantly improved results and therefore would enable
use at significantly lower dosages, demonstrating synergy in a
mixed peracid composition.
Example 12
[0277] The compatibility between peracetic acid and catalase
compositions and components of gel frac fluids were evaluated. The
changes in viscosity of the gel fluid upon addition of peracetic
acid with and without catalase were evaluated. Linear guar slurries
were initially prepared by hydration of guar polymers in standard
5-speed Waring blender. Deionized water was added and the mixture
was stirred until a homogeneous mixture was obtained. The linear
gels were cross-linked in the presence of borate based cross-linker
activators and peracetic acid with and without catalase. The
viscosity of the fluids was subsequently monitored at 275.degree.
F. for 200 minutes using a Grace 5500 rheometer with a R1B5
rotor-bob configuration.
[0278] The pass/fail criteria of the test were established as the
fluids maintaining a minimum viscosity of 200 cP for 120 minutes at
275.degree. F. The results shown in FIG. 18 demonstrate that
varying concentrations of peracetic acid between 1 ppm and 1000 ppm
along with varying concentrations of catalase between 1 ppm and 200
ppm were tested. FIG. 18 shows that hydrogen peroxide removal is
critical for the viscosity of the gel to remain above 200 cP for
the required time. Excess peracetic acid and hydrogen peroxide
(e.g. insufficient catalase) in a system failed to sustain the
viscosity above 200 cP for the required time. Testing could not be
performed with peracetic acid and hydrogen peroxide alone (i.e.
without catalase or other peroxide-reducing agent) as the product
prevented a gel from being formed. This is considered a fail and
would not be compatible for field use.
Example 13
[0279] The concentration of peracid compositions was evaluated to
determine the peroxide-reducing capability of enzymes. A catalase
enzyme was evaluated for efficacy in reducing hydrogen peroxide at
varying concentrations under increasingly concentrated peracid
compositions. The commercially-available peracid (POAA) composition
EnviroSan (Ecolab, Inc., St. Paul, Minn.) was evaluated using
catalase enzymes added to 2%, 3%, and 5% peracid compositions. The
catalase enzymes were added to the POAA solution and gently stirred
under ambient conditions. After the addition of catalase, the
stirring was discontinued, and the samples were taken for
iodometric assay.
[0280] As shown in Table 16, the peroxide-reducing enzymes
demonstrated efficacy in removing hydrogen peroxide from the
peracid composition at peracid levels as high as 3% POAA; however
no impact was observed at the level of 5% POAA.
TABLE-US-00020 TABLE 16 2% POAA 3% POAA 3% POAA 5% POAA Time 1500
ppm 1500 ppm 2500 ppm 1500 ppm (min.) Catalase Catalase Catalase
Catalase 0 2.0% POAA 3.0% POAA 2.0% POAA 5.0% POAA 1.36% H2O2 2.04%
H2O2 2.04% H2O2 3.40% H2O2 6.5 2.05% POAA 2.97% POAA 2.99% POAA
4.96% POAA 0.08% H2O2 0.33% H2O2 0.33% H2O2 3.81% H2O2 10 NA 2.83%
POAA 2.95% POAA NA 0.23% H2O2 0.23% H2O2 15 NA 2.95% POAA 2.87%
POAA NA 0.21% H2O2 0.21% H2O3
Example 14
[0281] Differing processes of forming antimicrobial reduced
peroxide compositions according to embodiments of the invention
were evaluated to determine process effects on the
peroxide-reducing capability of enzymes. A first process (A)
combined a peracid composition to a solution containing catalase
enzyme. To 392 grams of DI water was added 1.5 mL of ES 2000
catalase, then 107.37 grams of EnviroSan (POAA) peracid composition
was slowly added to the solution during a period of 5 minutes
without stirring.
[0282] A second process (B) added a catalase composition to a
diluted peracid composition. To the solution of 107.37 grams of
EnviroSan (POAA) peracid composition in 392 grams of DI water, 0.5
mL of ES 2000 catalase was added during a period of 5 minutes
without stirring.
[0283] As shown in Table 17, the process of adding the
peroxide-reducing enzymes impacted the efficacy of the hydroxide
removal from the POAA peracid compositions. As further shown in
FIG. 19, the mixture of POAA and 1H.sub.2O.sub.2 is preferably
added to the catalase solution to achieve the maximum efficiency of
hydrogen peroxide removal/reduction.
TABLE-US-00021 TABLE 17 Time A B (min.) POAA % H2O2 % POAA % H2O2 %
0 3.00 2.24 3.00 2.24 10 3.01 0.46 3.12 2.22 20 3.01 0.46 3.06 2.26
45 3.30 0.32 2.99 2.17 60 2.96 0.48 3.02 2.13
Example 15
[0284] Field of use applications were analyzed to determine the
amount of a peroxide-reducing enzyme necessary to obtain desired
concentrations of both peracid and hydrogen peroxide in a treated
water source. EnviroSan (POAA) peracid composition was added to
water to reach the targeted POAA concentrations set forth in Table
18, and the concentration of both POAA and H.sub.2O.sub.2 were
confirmed by iodometric titration. Then catalase (ES2000) was added
to the solution, and the sample was stored under ambient
conditions. The concentration of POAA and H.sub.2O.sub.2 were
monitored by the iodometric conditions.
[0285] As shown in Table 18, the pond water with POAA and
H.sub.2O.sub.2 could be treated with as low as 0.5 ppm catalase
within 4 hours. The results further demonstrate that higher levels
(concentrations) of catalase work more efficiently in decomposing
H.sub.2O.sub.2 from the peracid composition. Regardless,
approximate 1 ppm catalase is sufficient for treating the water
source. In addition, the results show that under the tested ambient
conditions, catalase selectively decomposes the H.sub.2O.sub.2
without having any negative impact on POAA stability.
TABLE-US-00022 TABLE 18 Catalase (ppm) Time (hr). POAA (ppm) H2O2
(ppm) 0.5 0 14.6 12.0 0.5 1 15.0 7.5 0.5 2 14.3 6.5 0.5 3.6 14.2
1.8 0.5 0 31.1 22.8 0.5 1 32.0 12.2 0.5 2 29.2 7.8 0.5 3.6 30.6 3.4
1.0 0 14.8 12.6 1.0 1 14.6 3.7 1.0 2 14.2 1.1 1.0 3.6 15.9 0.4 1.0
0 30.1 23.3 1.0 1 31.0 7.6 1.0 2 29.6 2.3 1.0 3.6 29.3 0.0
Example 16
[0286] The stability of treated peracid compositions according to
the invention was evaluated to determine the impact of acidulants
on compositional stability. pH adjustments to POAA compositions
were made using various acidulants to decrease the pH of the
peracid compositions as a means of pretreating the compositions
prior to use according to the various methods of the invention. The
EnviroSan (POAA) peracid composition was pretreated with the
following materials to assess the impact on the stability of POAA:
chlorine dioxide (ClO.sub.2), catalase, or nitric acid (HNO.sub.3).
The following methods were employed to test the stability (as
measured by remaining ppm POAA) of the peracid compositions in
20/80 water (produced/5 grain water), as set forth in Table 19.
[0287] The chlorine dioxide (100 ppm) was added as a pretreatment
to 100 ml of 100% produced water. Two hours elapsed before the 1%
EnviroSan was added and POAA stability was tested in the acidified
water source to be treated according to the invention.
[0288] The catalase pretreatment consisted of adding 1% EnviroSan
to 100 ppm catalase. The solution was stirred for 6.5 minutes
before POAA stability was tested.
[0289] The pretreatment of 100 ml of 100% produced water with the
acid (diluted HNO.sub.3 to pH 2.5) included stirring the solution
magnetically for .about.1 hour. Then 20 g of the acidified water to
be treated according to the invention was mixed with 80 g of 5
grain water, and the pH of the solution was adjusted from 5.5 to
6.6 before adding the 1% EnviroSan for POAA stability testing.
[0290] No acidification and/or pretreatment of the water source was
conducted for the Control experiment.
TABLE-US-00023 TABLE 19 Sample Time Catalase ClO.sub.2 Acid (min.)
Control Pretreated Pretreated* Pretreated 0 27 27 28 28 1 14 22 28
26 4 3 20 29 19 5 2 19 28 22 6 0 20 29 22 *Minor interference
observed in iodometric titration
[0291] As shown in FIG. 20, there is a clear benefit for use of an
acidulant with the treated peracid compositions according to the
invention in order to improve the peracid stability. The improved
stability (ppm POAA over elapsed time) shown demonstrates that a
pretreatment of a water source to decrease the pH of the water to
be acidic, results in prolonged peracid stability.
Example 17
[0292] To a water mixture of 80/20 (5 grain/produced water) was
added the various peracid compositions with stirring. The level of
peracid at specific times was assayed by iodometric titration. The
following peracid compositions were employed: EnviroSan: 60
microliter/100 g (POAA, 13.97%, H.sub.2O.sub.2, 10.41%); Low
Peroxide POAA: 65 microliter/100 g (POAA 12.72, H.sub.2O.sub.2,
1.55%); and EnviroSan/HAC (i.e. Acidified EnviroSan): 60 microliter
EnviroSan plus 25 microliter/Hac/100 g.
[0293] For catalase treatment, 0.3 g of ES 2000 was added to 78.53
g of water, then 21.47 g of EnviroSan was added in the solution
without stirring. At the end of the addition the peracid and
hydrogen peroxide concentrations were assayed (POAA 2.77%,
H.sub.2O.sub.2 0.51%). The results are shown in Table 20.
TABLE-US-00024 TABLE 20 Time W POAA Sample (min.) (g) V.sub.(ml,
0.1NNa2S2O3) (ppm) pH EnviroSan 0 94 6.30 1 21.08 0.47 85 2 18.19
0.30 63 3 17.62 0.24 52 4 20.51 0.24 44 5 21.78 0.22 38 Low
Peroxide 0 90 5.42 POAA 1 21.78 0.48 84 2 22.36 0.48 82 3 18.95 0.4
80 4 19.61 0.42 81 5 18.11 0.39 82 Envirosan- 0 94 5.38 HAc 1 21.73
0.48 84 (i.e. acidified) 2 17.94 0.40 85 3 17.97 0.38 80 4 18.07
0.38 80 5 21.22 0.42 75 EnviroSan 0 90 6.18 (3% POAA)- 1 17.92 0.38
81 Catalase 2 17.96 0.34 72 3 18.5 0.32 66 4 19.75 0.31 60 5 23.97
0.36 57
[0294] Again as shown in FIG. 21, there is a clear benefit for use
of an acidulant with the treated peracid compositions according to
the invention in order to improve the peracid stability.
Example 18
[0295] An inorganic metal peroxide-reducing agent was evaluated for
its specificity of reducing hydrogen peroxide in peracid
compositions in comparison to peracid reduction. As shown in Table
21, various POAA compositions with varying starting concentrations
of hydrogen peroxide were contacted with a platinum (Pt) catalyst.
The tested compositions were generated as follows: Composition A
(2000 ppm POAA plus 250 ppm H.sub.2O.sub.2; 0.2166% w/w peracid,
0.0034 wt-% measured H.sub.2O.sub.2); Composition B (2000 ppm POAA
plus 500 ppm H.sub.2O.sub.2; 0.2166% w/w peracid, 0.0094 wt-%
measured H.sub.2O.sub.2); Composition C (2000 ppm POAA plus 1000
ppm H.sub.2O.sub.2; 0.2138% w/w peracid, 0.0340 wt-% measured
H.sub.2O.sub.2); Composition D (2000 ppm POAA plus 2000 ppm
H.sub.2O.sub.2; 0.2119% w/w peracid, 0.0540 wt-% measured
H.sub.2O.sub.2).
[0296] A zeolite (i.e. a porous structure that can accommodate a
wide variety of cations and are used in formulating catalysts) was
used to suspending a sample of an inorganic metal peroxide-reducing
agent. The zeolite was saturated with various metal
peroxide-reducing agents (as set forth in the various different
examples) in a solution of peracetic acid. The zeolites that were
employed are commonly used in the industry of hydrocarbon cracking
for catalysis. The concentrations of POAA and H.sub.2O.sub.2 were
then measured with an iodometric titration over time to show the
impact of the particular metal peroxide-reducing agent on selective
or non-selective degradation of POAA and/or H.sub.2O.sub.2.
[0297] Table 21 shows the comparison of the initial POAA
concentration and the final POAA concentration after 15 minutes
contact with the peroxide-reducing agent according to the invention
is shown in FIG. 22.
TABLE-US-00025 TABLE 21 Composition Peroxide Conc. initial POAA 15
minute POAA A 34 2166 1862 B 94 2166 1606 C 340 2138 1188 D 540
2119 817
[0298] As shown in Table 22, the decomposition rates of the POAA
concentration in the various peracid compositions are further
shown. As shown in both Table 22 and FIG. 23, as the concentration
of hydrogen peroxide increases the POAA loss rate similarly
increases. As a result, the peroxide-reducing agent provides a
partially selective peroxide decomposition from peracid
compositions.
TABLE-US-00026 TABLE 22 ppm H.sub.2O.sub.2 POAA loss rate 34
-20.267 94 -37.333 340 -63.33 540 -86.8
[0299] The results demonstrate the partial selectivity of the
inorganic peroxide-reducing agent platinum (Pt), suitable for use
according to the methods of the invention. The inorganic
peroxide-reducing agent was then evaluated in combination with the
peroxide-reducing enzyme agent catalase. The 2000 ppm POAA
compositions were measured at 0 minutes, 30 minutes, 60 minutes,
120 minutes and 240 minutes, as shown in Table 23 under the various
combinations with a catalase peroxide-reducing enzyme.
TABLE-US-00027 TABLE 23 POAA Concentration Time Catalase + Pt
Pretreated Pt Catalase only 0 1934 1934 1934 30 1824 1784 1891 60
1710 1615 1929 120 1406 1210 1877 240 874 608 1568
[0300] FIG. 24 graphically shows the results of the decrease in
POAA (e.g. peracid decomposition), showing that inorganic
peroxide-reducing agent results in less selective hydrogen peroxide
reduction or decomposition in comparison to the peroxide-reducing
enzyme catalase. However, the inorganic peroxide-reducing agent
provides a partially selective peroxide decomposition from peracid
compositions.
Example 19
[0301] Additional inorganic metals were evaluated for use as solid
catalysts for evaluation as peroxide decomposition catalysts
according to the methods of the invention. The metals tungsten (W),
zirconium (Zr), and ruthenium (Ru) were evaluated to determine
whether the metals preferentially reduce hydrogen peroxide
concentration over peracid concentration within a peracid
composition. Table 24 shows the various formulations evaluated over
4 hours.
TABLE-US-00028 TABLE 24 control WZr Ru control WZr Time POAA POAA
POAA H.sub.2O.sub.2 H.sub.2O.sub.2 Ru H.sub.2O.sub.2 0 1986 1986
1986 1547 1547 1547 15 1938 2252 513 1539 1267 0 60 1862 1330 228
1556 1071 0 240 1539 190 38 1509 327 0
[0302] As shown in FIG. 25 the decrease in both POAA (e.g. peracid
decomposition) and hydrogen peroxide are compared. Both inorganic
peroxide-reducing agents resulted in significant decrease in both
POAA and hydrogen peroxide, showing only a slight preference in
hydrogen peroxide decomposition over POAA.
Example 20
[0303] Various additional inorganic metals and metal compounds were
further evaluated for use as peroxide decomposition catalysts (e.g.
peroxide-reducing agents) according to the methods of the
invention. The metals were provided as solid catalysts to POAA
solutions.
[0304] Table 25 shows the various solutions that were tested
against 10 g CoMo, cobalt molybdenum peroxide-reducing agent
sample, including a POAA plus catalase peracid composition,
hydrogen peroxide plus acetic acid composition, hydrogen peroxide
composition.
TABLE-US-00029 TABLE 25 POAA Concentration H.sub.2O.sub.2
Concentration Equil. POAA + Equil. H.sub.2O.sub.2- POAA + Time POAA
catalase POAA H.sub.2O.sub.2 HOAc catalase 0 2014 2071 1836 1615
1572.5 0 15 570 136.8 54.4 1343 1462 68 30 45.6 106.4 0 1156 1351.5
6.8 45 0 0 0 994.5 1207 0 60 0 0 0 841.5 1062.5 0
[0305] As shown in FIGS. 26-27, the POAA loss (FIG. 26) and
hydrogen peroxide loss (FIG. 27) are a function of time of exposure
to the peroxide-reducing agent CoMo.
[0306] Table 26 shows the various solutions that were tested
against 10 g NiW, a nickel wolfram inorganic peroxide-reducing
agent sample, including a POAA plus catalase peracid composition,
hydrogen peroxide plus acetic acid composition, hydrogen peroxide
composition.
TABLE-US-00030 TABLE 26 POAA Concentration H2O2 Concentration
Equil. POAA + POAA POAA + H.sub.2O.sub.2- Equil. Time POAA catalase
Control catalase HOAc H.sub.2O.sub.2 POAA Control 0 2071 2014 2014
0 1572.5 1615 1836 1572.5 15 1976 1919 1938 0 1589.5 1581 1836
1589.5 30 1862 1786 1900 34 1589.5 1598 1751 1615 45 1710 1672 1881
68 1606.5 1615 1700 1640.5 60 1406 1539 1843 68 1606.5 1615 1632
1666
[0307] As shown in FIGS. 28-29 POAA loss (FIG. 28) and hydrogen
peroxide loss (FIG. 29) are a function of time in the presence of a
NiW peroxide-reducing agent.
[0308] Table 27 shows the various solutions that were tested
against 10 g NiMo, a nickel molybdenum inorganic peroxide-reducing
agent sample, including a POAA plus catalase peracid composition,
hydrogen peroxide plus acetic acid composition, hydrogen peroxide
composition.
TABLE-US-00031 TABLE 27 POAA Concentration H2O2 Concentration
Equil. POAA + POAA POAA + H.sub.2O.sub.2- Equil. Time POAA catalase
Control catalase HOAc H.sub.2O.sub.2 POAA Control 0 2071 2014 2014
0 1572.5 1615 1836 1572.5 15 1482 1254 1938 289 1589.5 1581 1377
1589.5 30 760 874 1900 450.5 1615 1555.5 1173 1615 45 1140 456 1881
612 1640.5 1530 782 1640.5 60 0 532 1843 544 1666 1496 0 1666
[0309] As shown in FIGS. 30-31 POAA loss (FIG. 30) and hydrogen
peroxide loss (FIG. 31) are a function of time in the presence of a
NiMo peroxide-reducing agent.
[0310] Additional testing using the NiMo, nickel molybdenum
inorganic peroxide-reducing agent was conducted using a different
titration methodology, due to some molybdenum metal leaching into
the POAA solution (e.g. potentially negative effects on the
POAA/hydrogen peroxide separation). To correct this, 2 separate 10
ml samples were collected at each time point during the test. One
of the samples was treated with a small amount (.about.1 mml) of
added catalase to eliminate the hydrogen peroxide in the solution.
The second solution was titrated for total oxygen content with
addition of oxygen catalyst, sulfuric acid and KI. As a result, the
titration volume from the catalase treated sample represents a
direct measurement of the POAA content in the solution, and the
total oxygen titration minus the catalase treated titration equals
the amount of peroxide in the solution. The results are outlined in
Table 28 and shown in FIGS. 32-33.
TABLE-US-00032 TABLE 28A Titration Total with Oxygen ppm ppm POAA
H.sub.2O.sub.2 time catalase titration POAA H.sub.2O.sub.2 control
control 0 5.2 15.65 1976 1776.5 2014 1572.5 15 0.5 5.3 190 816 1938
1589.5 30 0.3 4.9 114 782 1900 1615 45 0.2 4.4 76 714 1881 1640.5
60 0.2 4.2 76 680 1843 1666
TABLE-US-00033 TABLE 28B (Pre-treated POAA with catalase) Titration
Total with Oxygen ppm ppm POAA H.sub.2O.sub.2 time catalase
titration POAA H.sub.2O.sub.2 control control 0 5.3 5.3 2014 0 2014
0 15 0.2 2.4 76 374 1938 20 30 0.2 2.2 76 340 1900 40 45 0.08 1.9
30.4 309.4 1881 60 60 0.12 1.65 45.6 260.1 1843 80
[0311] Table 29 shows the various solutions that were tested
against 10 g Mo, a molybdenum inorganic peroxide-reducing agent
sample, including a POAA plus catalase peracid composition,
hydrogen peroxide plus acetic acid composition, hydrogen peroxide
composition.
TABLE-US-00034 TABLE 29 POAA Concentration H.sub.2O.sub.2
Concentration Equil. POAA + POAA POAA + H.sub.2O.sub.2- Equil. Time
POAA catalase Control catalase HOAc H.sub.2O.sub.2 POAA Control 0
2071 2014 2014 0 1572.5 1615 1836 1572.5 15 1482 988 1938 408 1530
1334.5 1615 1589.5 30 988 836 1900 493 1436.5 1181.5 1462 1615 45
684 608 1881 569.5 1317.5 986 1088 1640.5 60 0 418 1843 654.5 1190
841.5 0 1666
[0312] As shown in FIGS. 34-35 POAA loss (FIG. 34) and hydrogen
peroxide loss (FIG. 35) are a function of time in the presence of a
Mo peroxide-reducing agent.
[0313] Additional testing using the Mo, molybdenum inorganic
peroxide-reducing agent was conducted using a different titration
methodology, as outlined above with respect to the NiMo catalyst
testing that was re-analyzed. The results are outlined in Table 30
and shown in FIGS. 36-37.
TABLE-US-00035 TABLE 30A Titration Total with Oxygen ppm ppm POAA
H.sub.2O.sub.2 time catalase titration POAA H.sub.2O.sub.2 control
control 0 5.4 14.85 2052 1606.5 2014 1572.5 15 2.55 6 969 586.5
1938 1589.5 30 0.12 1.3 45.6 200.6 1900 1615 45 0.08 1 30.4 156.4
1881 1640.5 60 0.08 0.72 30.4 108.8 1843 1666
TABLE-US-00036 TABLE 30B (Pre-treated POAA with catalase) Titration
Total with Oxygen ppm ppm POAA H.sub.2O.sub.2 time catalase
titration POAA H.sub.2O.sub.2 control control 0 5.3 5.3 2014 0 2014
0 15 1.3 4.1 494 476 1938 20 30 0.4 3.4 152 510 1900 40 45 0.2 3.2
76 510 1881 60 60 0.2 3.1 76 493 1843 80
Example 21
[0314] Micro efficacy of peracid compositions utilizing various
peroxide-reducing agents according to embodiments of the invention
was analyzed, as shown in Table 31. The control sample was a
contaminated water source from a field water composition used in
the field of hydraulic fracturing (i.e. 73,412,793.2 micro
equivalents per gram contaminants). Peracid samples with and
without hypochlorite were added to the Control contaminated water
source and were tested to determine effect on micro efficacy of the
use of and sequencing of the potential peroxide-reducing agent. As
reference in this example, the POAA employed is a 15% peracetic
acid and 10% hydrogen peroxide composition (such as
commercially-available as EnviroSan). As set forth in Tables 31-32,
the reference to "X2" refers to a second sequence of dosing the
POAA and/or Hypochlorite to the Control contaminated water source.
For example, a first dose of 250 ppm POAA was added to treat the
Control contaminated water source and thereafter a second dose was
administered.
[0315] According to the Tables 31-32, the amount of active (ppm)
POAA and/or hypochlorite in the Control treated water sources is as
follows, for example: 250 ppm POAA is equivalent to 37.5 ppm POAA
in solution of the Control water source; 250 ppm hydrogen peroxide
is equivalent to 25 ppm hydrogen peroxide in solution of the
Control water source.
TABLE-US-00037 TABLE 31 ATP Sample Conc Volume (pg Micro % Sample
RLU.sub.UC1 (mL) RLU.sub.cATP ATP/g) Equivs/g) Reduction Control
11725 20 1721530 73412.8 73,412,793.2 Control with POAA 11725 10
5497 468.8 468,827.3 99% 250 ppm (X2) Control with Hypo 11725 10
38791 3308.4 3,308,400.9 95% 250 ppm (X2) Control with 11725 10
34071 2905.8 2,905,842.2 96% Hypo/POAA 250 ppm each Control with
11725 10 25606 2183.9 2,183,880.6 97% POAA/Hypo 250 ppm each
Control with Hypo 11725 10 58401 4980.9 4,980,895.5 93% 500 ppm
Control with POAA 11725 10 24795 2114.7 2,114,712.2 97% 500 ppm
[0316] Additional evaluation of the process of using
peroxide-reducing agents in sequence was further analyzed as shown
in Table 32 using additional water samples, including deionized
water (i.e. not contaminated), and the Control (as set forth above
as a contaminated water source).
TABLE-US-00038 TABLE 32 POAA POAA NaOCl NaOCl H2O2 H2O2 Time ppm
ppm ppm ppm ppm ppm % Samples (min) meas. calc. meas. calc. meas.
calc. Reduction DI H2O with Hypo 2 0.00 0 137.30 300 0.00 0 1000
ppm DI H2O with Hypo 2 0.00 0 149.02 300 0.00 0 1000 ppm DI H2O
with POAA 2 62.64 75 61.32 150 23.78 50 500 ppm/Hypo 500 ppm DI H2O
with POAA 2 69.54 75 68.07 150 31.95 50 500 ppm/Hypo 500 ppm DI H2O
with POAA 2 170.23 150 0.00 0 121.85 100 1000 ppm Control with POAA
30 24.52 75 0.00 0 40.74 50 99.4% 250 ppm (X2) Control with Hypo 30
0.00 0 7.20 150 0.00 0 95.5% 250 ppm (X2) Control with 30 1.85 37.5
3.62 75 19.87 25 96.0% Hypo/POAA 250 ppm each Control with 30 0.94
37.5 1.84 75 15.15 25 97.0% POAA/Hypo 250 ppm each Control with
Hypo 30 0.00 0 3.70 150 0.00 0 93.2% 500 ppm Control with POAA 30
3.77 75 0.00 0 37.12 50 97.1% 500 ppm DI H2O with POAA 30 82.12 75
0.00 0 66.80 50 250 ppm (X2) DI H2O with Hypo 30 0.00 0 81.84 150
0.00 0 250 ppm (X2) DI H2O with 30 33.84 37.5 33.13 75 6.73 25
Hypo/POAA 250 ppm each DI H2O with 30 35.90 37.5 35.15 75 6.76 25
POAA/Hypo 250 ppm each
[0317] The results shown in Table 32 demonstrate that hypochlorite
has efficacious impact on the decomposition of hydrogen peroxide
(in water not containing any biological contamination). The mixed
systems showed increased peroxide decomposition compared to the
non-mixed peracid systems. This demonstrates the effect of
biological contamination in water competing with hydrogen peroxide
decay by sodium hypochlorite. More rapid decomposition or decay of
the peracetic acid and sodium hypochlorite is observed in
conjunction with increased microbial percentage reduction while
hydrogen peroxide shows increased stability.
[0318] The peracetic acid and sodium hypochlorite are
indistinguishable in titration, and are therefore presumed to
consist of 1/2 of the titrateable material; however the focus of
the evaluation was solely on the hydrogen peroxide
decomposition.
Example 22
[0319] A field of use application was analyzed to determine
efficacy of the peroxide-reducing catalase enzyme in pond waters
under ambient conditions. Catalase (ES 2000) was used in a pond
water source (370000 barrel (bbl.)) to reduce/eliminate
H.sub.2O.sub.2 in a POAA peracid composition. The pond water when
sampled contained both POAA and H.sub.2O.sub.2. The treatments
analyzed were based on established laboratory data, which at 1 ppm
use level selectively eliminated H.sub.2O.sub.2 to zero within 4
hours. An initial catalase treatment in the pond water applied in
the late morning under clear weather conditions and ambient outdoor
temperatures in the 90.degree. F. (+) range did not result in any
significant elimination of the hydrogen peroxide as expected.
Therefore, 100 gram samples of the pond water were used to add
various levels of either 1 ppm catalase (Table 33) or 2 ppm
catalase (Table 34).
[0320] The samples were then stored at various conditions
identified: ambient room temperature, outside under sunlight,
outside shielded from sunlight. The level of hydrogen peroxide was
assayed at various times (shown at 0 hours and 2 hours) to check
the functionality of the catalase peroxide-reducing agent. As
referred to in the Tables, the following measurements are set forth
as follows: EP1 V (ml 0.05N Na.sub.2S.sub.2O.sub.3) and EP2 V (ml
0.05N Na.sub.2S.sub.2O.sub.3).
[0321] As shown in Tables 33-34, light has a significant negative
impact on the performance of catalase enzyme in reducing
H.sub.2O.sub.2 concentration from the peracid composition. The
results further demonstrate that the temperature under the
investigated conditions has positive impact on the catalase
functionality.
TABLE-US-00039 TABLE 33 Sample Time Weight POAA H.sub.2O.sub.2
Sample Store Conditions (hr.) (g) EP1 EP2 (ppm) (ppm) Treated water
Ambient Room 0.00 20 0.06 0.16 5.7 6.8 (1 ppm catalase) Outside
under the 0.00 20 0.06 0.16 5.7 6.8 sunlight Outside shield from
0.00 20 0.06 0.16 5.7 6.8 the sunlight Treated water Ambient Room
2.00 20 0.06 0.03 5.7 1.3 (1 ppm catalase) Outside under the 2.00
20 0.05 0.16 4.75 6.8 sunlight Outside shield from 2.00 20 0.06
0.02 5.7 0.9 the sunlight
TABLE-US-00040 TABLE 34 Sample Time Weight POAA H.sub.2O.sub.2
Sample Store Conditions (hr.) (g) EP1 EP2 (ppm) (ppm) Treated water
Ambient Room 0.00 20 0.06 0.16 5.7 6.8 (2 ppm catalase) Outside
under the 0.00 20 0.06 0.16 5.7 6.8 sunlight Outside shield from
0.00 20 0.06 0.16 5.7 6.8 the sunlight Treated water Ambient Room
2.00 20 0.06 0.00 5.7 0.0 (2 ppm catalase) Outside under the 2.00
20 0.05 0.10 4.75 4.3 sunlight Outside shield from 2.00 20 0.06 0.0
5.7 0.0 the sunlight
[0322] The results of the field trials demonstrate utility for the
inclusion of a UV-blocking agent for certain applications of use of
the peroxide-reducing agent, namely a peroxide-reducing enzyme,
such as catalase. A UV-blocking agent may alternatively be replaced
with methods of application that minimize the exposure to sunlight
(e.g. dosing the peroxide-reducing agent at a time with no and/or
weak sunlight, such as at night and/or cloudy periods of time). In
still other aspects, the field trials demonstrate applications of
use suitable for use of a dye as a UV-blocking agent to prevent the
penetration of sunlight into a water system in need of treatment
with the UV-blocking agent for the effective reduction of hydrogen
peroxide according to the invention.
[0323] The inventions being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the inventions
and all such modifications are intended to be included within the
scope of the following claims.
* * * * *